[1/3] omap4xxx: Allow custom DOMX source instead of Google DOMX default

Part 1 of 3 patches: To allow omap4 devices to use custom "domx" source
via a new BoardConfig.mk item:
TI_CUSTOM_DOMX_PATH := device/<manufacturer>/<device-name>/domx

This setting provides for 3 changes during the build:
1. In hardware/ti/omap4xxx this settings stops standard Google domx
source from being built and changes the domx reference for tiutils.
2. In frameworks/base it changes the default openmax references for
frameworks/base/media/jni/mediaeditor/Android.mk to the new location
3. In frameworks/av changes the openmax references in 5 places, and adds
new includes in ACodec.cpp, CameraSource.cpp and OMXCodec.cpp

This commit for hardware/ti/omap4xxx is based on this cherry-pick from
omapzoom (with a more descriptive BoardConfig setting name):
http://www.omapzoom.org/?p=platform/hardware/ti/omap4xxx.git;a=commitdiff;h=040534d546dbcfcff16ff1afff15c01c2822dfcc

Change-Id: I5ae4669ab388394d12741314c6c00312eba6732b