Disabled fallback to interpreter in dexfuzz.

Added the -Xno-dex-file-fallback option when running optimizing backends so
that it fails in case compilation fails.

Test: Introduce an artificial crash in the optimizing compiler. There should
be a divergence reported.
dexfuzz --input=Hello.dex --execute --arm --interpreter --optimizing --repeat=20 --dump-output

Change-Id: I8adfc68b176b7482efce0cc7335c3cc50857c5a2