lib: add libc and micro libc

lib/libc/include/stdio.h

@@ -0,0 +1,22 @@
+#ifndef STDIO_H_
+#define STDIO_H_
+
+#include <stdarg.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int snprintf(char *buffer, size_t count, const char *format, ...);
+extern int vsnprintf(
+	char *buffer,
+	size_t count,
+	const char *format,
+	va_list va);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

lib/libc/include/string.h

@@ -0,0 +1,14 @@
+#ifndef STRING_H_
+#define STRING_H_
+
+#include <stddef.h>
+
+extern size_t strlen(const char *s);
+
+extern int strcmp(const char *s1, const char *s2);
+extern int strncmp(const char *s1, const char *s2, unsigned long n);
+
+extern void *memset(void *str, int c, size_t n);
+extern void *memcpy(void *dst, const void *src, size_t len);
+
+#endif