Revert "Revert "Don't implicitly cast NULL to a bool""

This reverts commit 505388b8554d895aee107b7da770ff63474b436a.

Change-Id: I795141c00c5943f0f1fd0059fe6ab85e003ae224
Merge "Revert "Revert "Don't implicitly cast NULL to a bool""" into kitkat