Fix path to dlopen libmagic.
https://github.com/tytso/e2fsprogs/issues/133
--- lib/support/plausible.c.orig	2023-02-06 21:31:53.000000000 -0600
+++ lib/support/plausible.c	2023-02-26 16:12:16.000000000 -0600
@@ -62,7 +62,7 @@
 static int magic_library_available(void)
 {
 	if (!magic_handle) {
-		magic_handle = dlopen("libmagic.so.1", RTLD_NOW);
+		magic_handle = dlopen("@PREFIX@/lib/libmagic.dylib", RTLD_NOW);
 		if (!magic_handle)
 			return 0;