Add vprintf() in standard C library

This is a trivial, unoptimised implementation.

Change-Id: Ia05a3fbbc7582583f7e8ae06e464c96a6b4e766d
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/include/lib/stdlib/stdio.h b/include/lib/stdlib/stdio.h
index 80110a8..55d8fe2 100644
--- a/include/lib/stdlib/stdio.h
+++ b/include/lib/stdlib/stdio.h
@@ -59,6 +59,8 @@
 #define	EOF	(-1)
 
 int	 printf(const char * __restrict, ...) __printflike(1, 2);
+int	 vprintf(const char * __restrict, __va_list);
+
 int	 putchar(int);
 int	 puts(const char *);
 int	 sprintf(char * __restrict, const char * __restrict, ...)