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/arch/x86_64/crti.S

@@ -0,0 +1,16 @@
+/* x86-64 crti.s */
+.section .init
+.global _init
+.type _init, @function
+_init:
+	pushq %rbp
+	movq %rsp, %rbp
+	/* gcc will nicely put the contents of crtbegin.o's .init section here. */
+
+.section .fini
+.global _fini
+.type _fini, @function
+_fini:
+	pushq %rbp
+	movq %rsp, %rbp
+	/* gcc will nicely put the contents of crtbegin.o's .fini section here. */