minor: suppress GCC-4.9 erroneous warning on travis

See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750

Author: acmorrow

.travis.yml

@@ -67,7 +67,7 @@ before_script:
 
     # Build the driver and the tests
     - cd build
-    - ${CMAKE_BINARY} -DCMAKE_BUILD_TYPE=$CONFIG -DCMAKE_C_FLAGS="-Wall -Wextra -Wno-attributes -Werror" -DCMAKE_CXX_FLAGS="-Wall -Wextra -Wno-attributes -Werror" ..
+    - ${CMAKE_BINARY} -DCMAKE_BUILD_TYPE=$CONFIG -DCMAKE_C_FLAGS="-Wall -Wextra -Wno-attributes -Werror -Wno-error=missing-field-initializers" -DCMAKE_CXX_FLAGS="-Wall -Wextra -Wno-attributes -Werror -Wno-error=missing-field-initializers" ..
 
 script:
     - make