build: Do not warn about C99 extensions

Change-Id: Id2a612391120f0eeee9f527c633f49581afed47d
Refs: #1865
diff --git a/.waf-tools/default-compiler-flags.py b/.waf-tools/default-compiler-flags.py
index bdf3b19..96690b3 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']