Add ANDROID_RUNTIME_ROOT environment variable

This change adds an ANDROID_RUNTIME_ROOT environment variable
to indicate the root of the Android runtime. This can be
used in place of ANDROID_SYSTEM to locate files when they
move inside the runtime APEX.

Bug: 119935277
Test: build / boot
Change-Id: Ic3b1ae3e3c98eea7d7c59e514ce62994679ab7b7
1 file changed