Added a little safeguard against GCC optimizer bug to CMakeLists.txt.

7 jobs for gcc_optimizer_bug in 20 minutes and 39 seconds
Status Job ID Name Coverage
  Test
passed #10013
Linux
clang-c++11

00:20:38

passed #10015
Linux
clang-c++98

00:17:54

passed #10018
Linux
cppcheck

00:00:26

passed #10012
Linux
gcc-c++11

00:04:20

passed #10014
Linux
gcc-c++98

00:03:57

passed #10016
Apple
macos-c++11

00:16:23

passed #10017
Apple
macos-c++98

00:15:20