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/search.h

@@ -0,0 +1,36 @@
+#ifndef _SEARCH_H
+#define _SEARCH_H 1
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/search.h.html
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define __need_size_t
+#include <sys/types.h>
+
+typedef struct
+{
+	char* key;
+	void* data;
+} ENTRY;
+
+typedef enum { FIND, ENTER } ACTION;
+typedef enum { preorder, postorder, endorder, leaf } VISIT;
+
+int		hcreate(size_t nel);
+void	hdestroy(void);
+ENTRY*	hsearch(ENTRY item, ACTION action);
+void	insque(void* element, void* pred);
+void*	lfind(const void* key, const void* base, size_t* nelp, size_t width, int (*compar)(const void*, const void*));
+void*	lsearch(const void* key, void* base, size_t* nelp, size_t width, int (*compar)(const void*, const void*));
+void	remque(void* element);
+void*	tdelete(const void* __restrict key, void** __restrict rootp, int(*compar)(const void*, const void*));
+void*	tfind(const void* key, void* const* rootp, int(*compar)(const void*, const void*));
+void*	tsearch(const void* key, void** rootp, int(*compar)(const void*, const void*));
+void	twalk(const void* root, void (*action)(const void*, VISIT, int));
+
+__END_DECLS
+
+#endif