build: Do not warn about C99 extensions

Change-Id: I9a0ca5d47dc80bec99b6a456fc025b41428377dc
diff --git a/waf-tools/default-compiler-flags.py b/waf-tools/default-compiler-flags.py
index e6e13fa..5ffba5e 100644
--- a/waf-tools/default-compiler-flags.py
+++ b/waf-tools/default-compiler-flags.py
@@ -15,7 +15,7 @@
     if conf.options.use_cxx11:
         defaultFlags += ['-std=c++0x', '-std=c++11']
     else:
-        defaultFlags += ['-std=c++03']
+        defaultFlags += ['-std=c++03', '-Wno-variadic-macros', '-Wno-c99-extensions']
 
     defaultFlags += ['-pedantic', '-Wall', '-Wno-long-long', '-Wno-unneeded-internal-declaration',
                      '-Wno-c++11-extensions', '-Wno-nested-anon-types']