user: implement mlibc as the libc, finally.

It's finally done..

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

user/include/mlibc/tests/posix/rlimits.c

@@ -0,0 +1,26 @@
+#include <sys/resource.h>
+#include <stdio.h>
+#include <errno.h>
+#include <assert.h>
+#include <string.h>
+
+int main() {
+	struct rlimit getlim, setlim;
+
+    setlim.rlim_cur = 16;
+    setlim.rlim_max = 4096;
+
+	int ret = setrlimit(RLIMIT_NOFILE, &setlim);
+
+    if(ret == -1) {
+        fprintf(stderr, "%s\n", strerror(errno));
+		assert(!ret);
+	}
+
+    assert(!getrlimit(RLIMIT_NOFILE, &getlim));
+
+	assert(setlim.rlim_cur == getlim.rlim_cur);
+	assert(setlim.rlim_max == getlim.rlim_max);
+
+    return 0;
+}