musl doesn't implement GLOB_BRACE, simply disable it.

https://bugs.gentoo.org/922286
https://github.com/rpm-software-management/rpm/issues/2844
--- a/rpmio/rpmglob.c
+++ b/rpmio/rpmglob.c
@@ -33,6 +33,10 @@
 
 #include "debug.h"
 
+#ifndef GLOB_BRACE
+#define GLOB_BRACE 0
+#endif
+
 /* Return 1 if pattern contains a magic char, see glob(7) for a list */
 static int ismagic(const char *pattern)
 {