Remove callback at the end of consumer destructor

It turns out that 'finishInputEvent' was adding the fd back to the
looper. This caused an NPE because we were calling 'finishInputEvent' at
the end of the consumer destructor, thus leaving the callback in the
looper. The looper would hit an NPE whenever the fd signaled after that.

To fix this, we move the call to setFdEvents(0) to the very end of the
destructor. This way, we can be sure that the last thing that executes
is the removal of the fd from the Looper.

There is also a possibility that fd is signaled during the destructor
execution. Theoretically, this should be okay because the fd callbacks
are processed on the same thread as the one where destructor runs.
Therefore, the signals would only be processed after the destructor has
completed, which means the callback would be removed before it gets the
chance to execute.

Bug: 332613662
Test: TEST=libinput_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST --gtest_filter="*InputConsumerTest*"
Test: TEST=libutils_test; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Flag: EXEMPT bugfix
Change-Id: If5ac7a8eaf96e842d5d8e44008b9c1bff74e674e