clang-16 compiler complains with following error message in multiple
places:

  error: incompatible function pointer types passing 'int (struct dirent *)' to
        parameter of type 'int (*)(const struct dirent *)' [-Wincompatible-function-pointer-types]

  error: incompatible function pointer types passing
        'int (const void *, const void *)' to parameter of type 'int (*)(const struct dirent **, const struct dirent **)' [-Wincompatible-function-pointer-types]

This patch fixes all those places by correcting function pointer types
for scandir callbacks.

Bug: https://bugs.gentoo.org/870478

diff --git a/src/osdep/unix/mh.c b/src/osdep/unix/mh.c
index 0226b7a..ace2b32 100644
--- a/src/osdep/unix/mh.c
+++ b/src/osdep/unix/mh.c
@@ -103,8 +103,8 @@ long mh_copy (MAILSTREAM *stream,char *sequence,char *mailbox,
 	      long options);
 long mh_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data);
 
-int mh_select (struct direct *name);
-int mh_numsort (const void *d1,const void *d2);
+int mh_select (const struct direct *name);
+int mh_numsort (const struct direct **d1,const struct direct **d2);
 char *mh_file (char *dst,char *name);
 long mh_canonicalize (char *pattern,char *ref,char *pat);
 void mh_setdate (char *file,MESSAGECACHE *elt);
@@ -1194,7 +1194,7 @@ long mh_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data)
  * Returns: T to use file name, NIL to skip it
  */
 
-int mh_select (struct direct *name)
+int mh_select (const struct direct *name)
 {
   char c;
   char *s = name->d_name;
@@ -1209,7 +1209,7 @@ int mh_select (struct direct *name)
  * Returns: negative if d1 < d2, 0 if d1 == d2, postive if d1 > d2
  */
 
-int mh_numsort (const void *d1,const void *d2)
+int mh_numsort (const struct direct **d1,const struct direct **d2)
 {
   return atoi ((*(struct direct **) d1)->d_name) -
     atoi ((*(struct direct **) d2)->d_name);
diff --git a/src/osdep/unix/mix.c b/src/osdep/unix/mix.c
index fbf4a02..0964842 100644
--- a/src/osdep/unix/mix.c
+++ b/src/osdep/unix/mix.c
@@ -125,7 +125,7 @@ long mix_unsubscribe (MAILSTREAM *stream,char *mailbox);
 long mix_create (MAILSTREAM *stream,char *mailbox);
 long mix_delete (MAILSTREAM *stream,char *mailbox);
 long mix_rename (MAILSTREAM *stream,char *old,char *newname);
-int mix_rselect (struct direct *name);
+int mix_rselect (const struct direct *name);
 MAILSTREAM *mix_open (MAILSTREAM *stream);
 void mix_close (MAILSTREAM *stream,long options);
 void mix_abort (MAILSTREAM *stream);
@@ -140,8 +140,8 @@ THREADNODE *mix_thread (MAILSTREAM *stream,char *type,char *charset,
 long mix_ping (MAILSTREAM *stream);
 void mix_check (MAILSTREAM *stream);
 long mix_expunge (MAILSTREAM *stream,char *sequence,long options);
-int mix_select (struct direct *name);
-int mix_msgfsort (const void *d1,const void *d2);
+int mix_select (const struct direct *name);
+int mix_msgfsort (const struct direct **d1,const struct direct **d2);
 long mix_addset (SEARCHSET **set,unsigned long start,unsigned long size);
 long mix_burp (MAILSTREAM *stream,MIXBURP *burp,unsigned long *reclaimed);
 long mix_burp_check (SEARCHSET *set,size_t size,char *file);
@@ -587,7 +587,7 @@ long mix_rename (MAILSTREAM *stream,char *old,char *newname)
  * Returns: T if mix file name, NIL otherwise
  */
 
-int mix_rselect (struct direct *name)
+int mix_rselect (const struct direct *name)
 {
   return mix_dirfmttest (name->d_name);
 }
@@ -1146,7 +1146,7 @@ long mix_expunge (MAILSTREAM *stream,char *sequence,long options)
  * ".mix" with no suffix was used by experimental versions
  */
 
-int mix_select (struct direct *name)
+int mix_select (const struct direct *name)
 {
   char c,*s;
 				/* make sure name has prefix */
@@ -1165,7 +1165,7 @@ int mix_select (struct direct *name)
  * Returns: -1 if d1 < d2, 0 if d1 == d2, 1 d1 > d2
  */
 
-int mix_msgfsort (const void *d1,const void *d2)
+int mix_msgfsort (const struct direct **d1,const struct direct **d2)
 {
   char *n1 = (*(struct direct **) d1)->d_name + sizeof (MIXNAME) - 1;
   char *n2 = (*(struct direct **) d2)->d_name + sizeof (MIXNAME) - 1;
diff --git a/src/osdep/unix/mx.c b/src/osdep/unix/mx.c
index 4549527..994f12c 100644
--- a/src/osdep/unix/mx.c
+++ b/src/osdep/unix/mx.c
@@ -98,8 +98,8 @@ long mx_append (MAILSTREAM *stream,char *mailbox,append_t af,void *data);
 long mx_append_msg (MAILSTREAM *stream,char *flags,MESSAGECACHE *elt,
 		    STRING *st,SEARCHSET *set);
 
-int mx_select (struct direct *name);
-int mx_numsort (const void *d1,const void *d2);
+int mx_select (const struct direct *name);
+int mx_numsort (const struct direct **d1,const struct direct **d2);
 char *mx_file (char *dst,char *name);
 long mx_lockindex (MAILSTREAM *stream);
 void mx_unlockindex (MAILSTREAM *stream);
@@ -1110,7 +1110,7 @@ long mx_append_msg (MAILSTREAM *stream,char *flags,MESSAGECACHE *elt,
  * Returns: T to use file name, NIL to skip it
  */
 
-int mx_select (struct direct *name)
+int mx_select (const struct direct *name)
 {
   char c;
   char *s = name->d_name;
@@ -1125,7 +1125,7 @@ int mx_select (struct direct *name)
  * Returns: negative if d1 < d2, 0 if d1 == d2, postive if d1 > d2
  */
 
-int mx_numsort (const void *d1,const void *d2)
+int mx_numsort (const struct direct **d1,const struct direct **d2)
 {
   return atoi ((*(struct direct **) d1)->d_name) -
     atoi ((*(struct direct **) d2)->d_name);
diff --git a/src/osdep/unix/news.c b/src/osdep/unix/news.c
index 4cf5bb7..caa6785 100644
--- a/src/osdep/unix/news.c
+++ b/src/osdep/unix/news.c
@@ -76,8 +76,8 @@ long news_create (MAILSTREAM *stream,char *mailbox);
 long news_delete (MAILSTREAM *stream,char *mailbox);
 long news_rename (MAILSTREAM *stream,char *old,char *newname);
 MAILSTREAM *news_open (MAILSTREAM *stream);
-int news_select (struct direct *name);
-int news_numsort (const void *d1,const void *d2);
+int news_select (const struct direct *name);
+int news_numsort (const struct direct **d1,const struct direct **d2);
 void news_close (MAILSTREAM *stream,long options);
 void news_fast (MAILSTREAM *stream,char *sequence,long flags);
 void news_flags (MAILSTREAM *stream,char *sequence,long flags);
@@ -402,7 +402,7 @@ MAILSTREAM *news_open (MAILSTREAM *stream)
  * Returns: T to use file name, NIL to skip it
  */
 
-int news_select (struct direct *name)
+int news_select (const struct direct *name)
 {
   char c;
   char *s = name->d_name;
@@ -417,7 +417,7 @@ int news_select (struct direct *name)
  * Returns: negative if d1 < d2, 0 if d1 == d2, postive if d1 > d2
  */
 
-int news_numsort (const void *d1,const void *d2)
+int news_numsort (const struct direct **d1,const struct direct **d2)
 {
   return atoi ((*(struct direct **) d1)->d_name) -
     atoi ((*(struct direct **) d2)->d_name);
-- 
2.35.1