Libraries: Create top level directory for libraries.

Things were getting a little crowded in the project root, so this patch
moves the Lib*/ directories into Libraries/.

Libraries/LibC/sys/wait.cpp

@@ -0,0 +1,11 @@
+#include <assert.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+extern "C" {
+
+pid_t wait(int* wstatus)
+{
+    return waitpid(-1, wstatus, 0);
+}
+}