cc-tool: fix missing stdarg.h include on uClibc

This commit adds a patch to fix a missing <stdarg.h> include for
va_list.

Fixes:

  http://autobuild.buildroot.org/results/9c8/9c828b1da8983577f93bdfae5275fc5122ae874f/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/cc-tool/0001-add-missing-stdarg-include.patch

@@ -0,0 +1,18 @@
+Add missing <stdarg.h> include for va_list
+
+Fixes the build on uClibc.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+
+Index: b/src/common/log.h
+===================================================================
+--- a/src/common/log.h
++++ b/src/common/log.h
+@@ -13,6 +13,7 @@
+ 
+ #include <stdio.h>
+ #include <stdlib.h>
++#include <stdarg.h>
+ #include "common.h"
+ 
+ class Log