Disable C++ exceptions

All code is written with assumption that exceptions are not being used.

Change-Id: I4373deea150832763b7c5b9f5fa2748fcad0d626
Reviewed-on: https://weave-review.googlesource.com/1629
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
diff --git a/libweave_common.gypi b/libweave_common.gypi
index 49f7ff9..73d02fd 100644
--- a/libweave_common.gypi
+++ b/libweave_common.gypi
@@ -31,6 +31,7 @@
     ],
     'cflags!': ['-fPIE'],
     'cflags': [
+      '-fno-exceptions',
       '-fPIC',
       '-fvisibility=hidden',
       '-std=c++11',