BuildSystem: Move all userpace libraries under the userspace directory

As the number of libraries is increasing, root directory starts to
expand. This adds better organization for libraries

userspace/libraries/LibC/include/fnmatch.h

@@ -0,0 +1,19 @@
+#ifndef _FNMATCH_H
+#define _FNMATCH_H 1
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/fnmatch.h.html
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define FNM_NOMATCH		1
+#define FNM_PATHNAME	0x01
+#define FNM_PERIOD		0x02
+#define FNM_NOESCAPE	0x04
+
+int fnmatch(const char* pattern, const char* string, int flags);
+
+__END_DECLS
+
+#endif