product_config: Set CM_BUILD priority above TARGET_BUILD_APPS

Even if we are doing TARGET_BUILD_APPS, we may want to use a cm
target for building.

Change-Id: Ic8053bc679fa8b726be90e611aeaacdf1850cabc
Merge branch 'cm-11.0' into kk_mkt

Conflicts:
	core/product_config.mk

Change-Id: Ia22f212e407cf2e9ed0025bf55c692c23e0010d0