Build time increased significantly with -Og

[pcolberg]

Since enabling -Og as part of #48, debug build times in CI and locally have increased noticeably compared to release builds. The build stalls particularly on the following compilation unit, which takes roughly four minutes here using GCC 7.4.0:

g++ -DACL_TARGET_BIT=64 -DCL_TARGET_OPENCL_VERSION=300 -DCL_USE_DEPRECATED_OPENCL_1_0_APIS=1 -DCL_USE_DEPRECATED_OPENCL_1_1_APIS=1 -DCL_USE_DEPRECATED_OPENCL_1_2_APIS=1 -DNOMINMAX -DUT_MALLOC_MACROS_DISABLED -DUT_NEW_MACROS_DISABLED -DUT_NEW_OVERRIDES_DISABLED -D_GLIBCXX_USE_CXX11_ABI=0 -Iinclude -I../../src -I../../include -I../../lib/acl_check_sys_cmd/include -I../../lib/acl_hash/include -I../../lib/acl_threadsupport/include -I../../lib/CppUTest/include -I../../lib/pkg_editor/include -g -Wall -Wconversion -Wformat -Wformat-security -fno-strict-aliasing -fstack-protector -D_FORTIFY_SOURCE=2 -Og -std=c++1z -MD -MT test/CMakeFiles/acl_test.dir/acl_globals_test.cpp.o -MF test/CMakeFiles/acl_test.dir/acl_globals_test.cpp.o.d -o test/CMakeFiles/acl_test.dir/acl_globals_test.cpp.o -c ../../test/acl_globals_test.cpp