Fix GCC 15 build failures; cherry-picked from upstream commits:
- 6466b0b (hlink.c: fix function pointer cast in qsort)
- 1ad3f70 (lib/pool_alloc.c: fix bomb function pointer declaration)
- 7ea8fe71 (configure.ac: fix gettimeofday tz-argument detection)

--- a/hlink.c
+++ b/hlink.c
@@ -121,7 +121,7 @@ static void match_gnums(int32 *ndx_list, int ndx_count)
 	int32 gnum, gnum_next;

 	qsort(ndx_list, ndx_count, sizeof ndx_list[0],
-	     (int (*)()) hlink_compare_gnum);
+	     (int (*)(const void*, const void*)) hlink_compare_gnum);

         if ( inc_recurse && prior_hlinks && hlink_nlinks ) {
             for (from = 0; from < ndx_count; from++) {
--- a/lib/pool_alloc.c
+++ b/lib/pool_alloc.c
@@ -9,7 +9,7 @@
 	size_t			size;		/* extent size		*/
 	size_t			quantum;	/* allocation quantum	*/
 	struct pool_extent	*extents;	/* top extent is "live" */
-	void			(*bomb)();	/* function to call if
+	void			(*bomb)(const char *);	/* function to call if
 						 * malloc fails		*/
 	int			flags;

--- a/lib/compat.c
+++ b/lib/compat.c
@@ -148,11 +148,7 @@
 /* some systems don't take the 2nd argument */
 int sys_gettimeofday(struct timeval *tv)
 {
-#ifdef HAVE_GETTIMEOFDAY_TZ
 	return gettimeofday(tv, NULL);
-#else
-	return gettimeofday(tv);
-#endif
 }

 #define HUMANIFY(mult) \

--- a/configure.ac
+++ b/configure.ac
@@ -852,7 +852,8 @@

 AC_CACHE_CHECK([if gettimeofday takes tz argument],rsync_cv_HAVE_GETTIMEOFDAY_TZ,[
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/time.h>
-#include <unistd.h>]], [[struct timeval tv; exit(gettimeofday(&tv, NULL));]])],[rsync_cv_HAVE_GETTIMEOFDAY_TZ=yes],[rsync_cv_HAVE_GETTIMEOFDAY_TZ=no])])
+#include <unistd.h>
+#include <stdlib.h>]], [[struct timeval tv; exit(gettimeofday(&tv, NULL));]])],[rsync_cv_HAVE_GETTIMEOFDAY_TZ=yes],[rsync_cv_HAVE_GETTIMEOFDAY_TZ=no])])
 if test x"$rsync_cv_HAVE_GETTIMEOFDAY_TZ" != x"no"; then
     AC_DEFINE(HAVE_GETTIMEOFDAY_TZ, 1, [Define to 1 if gettimeofday() takes a time-zone arg])
 fi