user: implement mlibc as the libc, finally.

It's finally done..

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

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

@@ -0,0 +1,41 @@
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#ifdef USE_HOST_LIBC
+#define TEST_FILE "fputs-host-libc.tmp"
+#else
+#define TEST_FILE "fputs.tmp"
+#endif
+
+int main() {
+	FILE *file;
+	char str[] = "mlibc fputs test";
+	char buffer[100];
+
+	// Clear the buffer to zero.
+	memset(buffer, 0, sizeof(buffer));
+
+	// Open the file for writing.
+	file = fopen(TEST_FILE, "w");
+	assert(file);
+
+	// Verify that we can write an empty string.
+	assert(fputs("", file) != EOF);
+
+	// Write string, flush and close.
+	assert(fputs(str, file) != EOF);
+	fflush(file);
+	fclose(file);
+
+	// Open the file for reading.
+	file = fopen(TEST_FILE, "r");
+	assert(file);
+
+	// Verify that we read back the written string and close.
+	assert(fread(buffer, 1, sizeof(str) - 1, file));
+	assert(!strcmp(buffer, str));
+	fclose(file);
+
+	return 0;
+}