user: implement mlibc as the libc, finally.

It's finally done..

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

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

@@ -0,0 +1,23 @@
+#include <assert.h>
+#include <errno.h>
+#include <sched.h>
+#include <unistd.h>
+
+int main() {
+	struct sched_param param = {
+		.sched_priority = 100,
+	};
+
+	int ret = sched_getparam(getpid(), &param);
+	assert(!ret);
+
+	ret = sched_setparam(getpid(), &param);
+	assert(ret == 0);
+
+	param.sched_priority = 0xD00DFEED;
+
+	ret = sched_setparam(getpid(), &param);
+	assert(ret == -1 && errno == EINVAL);
+
+	return 0;
+}