memrchr: fix compilation

compat/memrchr.c

@@ -20,7 +20,6 @@
 #endif
 
 #include <string.h>
-#include <stddef.h>
 
 /*
  * Reverse memchr()

include/vlc_fixups.h

@@ -77,6 +77,7 @@ typedef struct
 #endif
 
 #if !defined (HAVE_POSIX_MEMALIGN) || \
+    !defined (HAVE_MEMRCHR) || \
     !defined (HAVE_STRLCPY) || \
     !defined (HAVE_STRNDUP) || \
     !defined (HAVE_STRNLEN) || \
@@ -139,6 +140,10 @@ int vasprintf (char **, const char *, va_list);
 int ffsll(unsigned long long);
 #endif
 
+#ifndef HAVE_MEMRCHR
+void *memrchr(const void *, int, size_t);
+#endif
+
 #ifndef HAVE_STRCASECMP
 int strcasecmp (const char *, const char *);
 #endif
@@ -268,10 +273,6 @@ int unsetenv (const char *);
 int posix_memalign (void **, size_t, size_t);
 #endif
 
-#ifndef HAVE_MEMRCHR
-void *memrchr(const void *, int, size_t);
-#endif
-
 /* locale.h */
 #ifndef HAVE_USELOCALE
 #define LC_ALL_MASK      0