Use C23 __has_include to add correct include on musl. Was compiler extension
before C23, works on clang/gcc versions we care about.
https://bugs.gentoo.org/898564
--- a/src/libply/ply-command-parser.c	2025-02-26 14:05:33.417781845 +0000
+++ b/src/libply/ply-command-parser.c	2025-02-26 14:09:10.068476721 +0000
@@ -29,6 +29,10 @@
 #include <stdlib.h>
 #include <string.h>
 
+#if __has_include(<rpmatch.h>)
+#include <rpmatch.h>
+#endif
+
 #include "ply-buffer.h"
 #include "ply-list.h"
 #include "ply-utils.h"