user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/tests/rtld/scope1/libbar.c

@@ -0,0 +1,14 @@
+char *foo(void);
+char *foo_global(void);
+
+char *bar(void) {
+	return "bar";
+}
+
+char *bar_calls_foo(void) {
+	return foo();
+}
+
+char *bar_calls_foo_global(void) {
+	return foo_global();
+}