libc: io: implement file io buffering and internal locking for concurrency

lib/libc/io/stdio/printf.c

@@ -0,0 +1,12 @@
+#include <stddef.h>
+#include <stdio.h>
+
+int printf(const char *format, ...)
+{
+	va_list arg;
+	va_start(arg, format);
+	int ret = vprintf(format, arg);
+	va_end(arg);
+
+	return ret;
+}