Fix the x86 build.

We're not currently building V8 for x86, and mock-ril was changed to
depend on it.  This updates the makefile to skip building mock-ril on
non-ARM builds (e.g. sim-eng).

Change-Id: I50e1b6859d4d221316c87c2fdd5cb4d29fa5afbf
1 file changed