Revert "Add generator expressions for compiler versions."

This reverts commit 166bbb6636778167f9a94fbbc6a818bba388a236.
Revert "Escape individual COMPILE_OPTIONS entries."

This reverts commit b528f1c41b51d62c0dbdcddbdd0f3266ccb35506.
Merge topic 'compiler-version-genex' into next

381e35c Revert "Escape individual COMPILE_OPTIONS entries."
ecef8fb Revert "Add generator expressions for compiler versions."