message: Ignore -Wmaybe-uninitialized on GCC. Refs
diff: @@ -212,7 +212,7 @@ if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  -Wno-unknown-pragmas
  -Wno-reorder)
  if(CMAKE_COMPILER_IS_GNUCXX)
  - list(APPEND warning_flags -Wno-unused-but-set-variable)
  + list(APPEND warning_flags -Wno-unused-but-set-variable -Wno-maybe-uninitialized)
  # We keep the implicit fallthrough warning for now, but allow more
  # comments to silence it.
  