Disable -Wcast-function-type-mismatch am: 3c6ffd29b2

Original change: https://android-review.googlesource.com/c/platform/external/gflags/+/3499334

Change-Id: Ib338c85aa9dca8bf6517ca0ca6a9e1b95dbae78a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>