wm: Make the default menu longpress action configurable at build time

Do the same we do for home. For CDD validation, we need to switch
the menu and home longpress action, since Home must map to Google Now.

Change-Id: Iacfedf711d43f6637023c87c00e6c6b8b8a437dc

Conflicts:
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java