user: implement mlibc as the libc, finally.

It's finally done..

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

user/include/mlibc/tests/glibc/error.py

@@ -0,0 +1,11 @@
+import subprocess
+import sys
+import os
+from pyexpect import expect
+
+wrapper = os.getenv("MESON_EXE_WRAPPER")
+wrapper = [x for x in (wrapper,) if x]
+
+output = subprocess.check_output(wrapper + [sys.argv[1]], stderr=subprocess.STDOUT)
+
+expect(bytes(sys.argv[1], 'utf-8') + b': test: error: Invalid argument (EINVAL)\n').to_equal(output)