fix compile error
add option to build LPA support in addition to legacy OMX

LPA works on msm7x27a devices which uses ION.
However, legacy OMX stuff is still needed on these targets.

Change-Id: I3e104c005a6522ce314a96045930935aa322ea7f

Conflicts:
	media/libstagefright/Android.mk
	services/audioflinger/Android.mk