TargetMachine: Indicate whether machine verifier passes.

This adds a callback to the LLVMTargetMachine that lets target indicate
that they do not pass the machine verifier checks in all cases yet.

This is intended to be a temporary measure while the targets are fixed
allowing us to enable the machine verifier by default with
EXPENSIVE_CHECKS enabled!

Differential Revision: https://reviews.llvm.org/D33696

llvm-svn: 304320
diff --git a/llvm/lib/Target/Lanai/LanaiTargetMachine.h b/llvm/lib/Target/Lanai/LanaiTargetMachine.h
index 5278c70..083ba6f 100644
--- a/llvm/lib/Target/Lanai/LanaiTargetMachine.h
+++ b/llvm/lib/Target/Lanai/LanaiTargetMachine.h
@@ -49,6 +49,10 @@
   TargetLoweringObjectFile *getObjFileLowering() const override {
     return TLOF.get();
   }
+
+  bool isMachineVerifierClean() const override {
+    return false;
+  }
 };
 } // namespace llvm