user: implement mlibc as the libc, finally.

It's finally done..

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

user/include/mlibc/tests/ansi/fgetpos.c

@@ -0,0 +1,35 @@
+#include <assert.h>
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+	(void) argc;
+
+	FILE *f = fopen(argv[0], "r");
+	assert(f);
+
+	int ret = fseek(f, 0, SEEK_SET);
+	assert(!ret);
+
+	fpos_t start_pos;
+	ret = fgetpos(f, &start_pos);
+	assert(!ret);
+
+	ret = fseek(f, 0, SEEK_END);
+	assert(!ret);
+
+	long end_off = ftell(f);
+
+	fpos_t end_pos;
+	ret = fgetpos(f, &end_pos);
+	assert(!ret);
+
+	ret = fsetpos(f, &start_pos);
+	assert(!ret);
+	assert(ftell(f) == 0);
+
+	ret = fsetpos(f, &end_pos);
+	assert(!ret);
+	assert(ftell(f) == end_off);
+
+	return 0;
+}