Navbar : Fix left over glow

Invalidate all buttons, to avoid nearby glow interference

Change-Id: I83ab05b91bd5db70390a5c9480513768864a2be7
Merge "Navbar : Fix left over glow" into cm-10.1
Merge branch 'cm-10.1' of git://github.com/CyanogenMod/android_frameworks_base into cm-10.1