ART: Remove computed-goto interpreter

ART currently has 3 interpreters: a baseline switch-statement based
interpreter, a C++ computed goto interpreter and a fast assembly
interpreter (mterp).

The C++ computed goto interpreter was intended to get some of the
benefits of the old Dalvik mterp interpreter - which it did.  However,
we now have the faster assembly interpreter, so it is no longer
needed.

Test: m test-art-host
Test: m ART_TEST_INTERPRETER=true test-art-host
Change-Id: I0e8f139ab6bc48d0568951af1f83e2b1c00835f8