[PATCH] MC: provide the ability to disable assembly parsing

[Rafael Ávila de Espíndola]

  Others have commented on the "should we do it" issue. Assuming we do, the patch should probably

  * Use setUseIntegratedAssembler instead of creating a new flag.
  * Remove NoIntegratedAssembler from LLVMTargetMachine.cpp. We should have one way of disabling it.

http://llvm-reviews.chandlerc.com/D2839