Revert "Disable -Wno-single-bit-bitfield-constant-conversion locally" am: c667749398

Original change: https://android-review.googlesource.com/c/platform/external/python/cpython2/+/3249252

Change-Id: I2e0efbc2e634f881b2effbf07fcf3fe32389153f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>