Handle non-split pointers for multi-device case

During multi-device event stream, tempTouchState will already contain
some pointers from another case. When the second device becomes active
and tries to add pointers to a non-splitting window, we should not be
marking that pointer as going to the second window unless it's already
receiving pointers for that device.

Fixes: 341869464
Flag: EXEMPT bugfix
Test: TEST=inputflinger_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Change-Id: Ia295c1d9d941383792e90a3d6fd981473af8f015