Revert "graphite: Disable libstagefright_amrwbenc"

This error doesn't occur on Ubuntu systems only Debian.
Since Ubuntu is officially supported in AOSP but not Debian,
disabling graphite for libstagefright_amrwbenc doesn't seem necessary.

This reverts commit 343844707c01afe5ea6982a1bb4555c722a9072f.