Support GCC 4.7

Removed constructors inheritance.
Removed emplace use.

Change-Id: I45224e3232d39ff22f758c7e387be2c9aff5eae0
Reviewed-on: https://weave-review.googlesource.com/1606
Reviewed-by: Vitaly Buka <vitalybuka@google.com>
diff --git a/libweave_common.gypi b/libweave_common.gypi
index 73d02fd..4b12363 100644
--- a/libweave_common.gypi
+++ b/libweave_common.gypi
@@ -17,7 +17,7 @@
           '_DEBUG',
         ],
         'cflags': [
-          '-Og',
+          '-O0  ',
           '-g3',
         ],
       },