Bug 1008: improve handling of fast-math mode for older gcc versions.
Bug 1008: improve handling of fast-math mode for older gcc versions.

ROCmSoftwarePlatform/hipeigen,ROCmSoftwarePlatform/hipeigen,pasuka/eigen,pasuka/eigen,pasuka/eigen,ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,ritsu1228/eigen,pasuka/eigen,ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,ritsu1228/eigen,ritsu1228/eigen,pasuka/eigen