Prevent extra calls to ToggleFeature for Feature64Bit and FeatureCMOV if they've already been enabled. The extra call ends up clearing the bit in FeatureBits since its a 'toggle'. Can't prove that anything was broken because of this since I don't think the FeatureBits for these are used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190920 91177308-0d34-0410-b5e6-96231b3b80d8