Prune a LegacyDivergenceAnalysis and MachineLoopInfo include each

Now X86ISelLowering doesn't depend on many IR analyses.

llvm-svn: 375320
diff --git a/llvm/lib/Target/ARM/ARMBasicBlockInfo.h b/llvm/lib/Target/ARM/ARMBasicBlockInfo.h
index d0f4a02..13df399 100644
--- a/llvm/lib/Target/ARM/ARMBasicBlockInfo.h
+++ b/llvm/lib/Target/ARM/ARMBasicBlockInfo.h
@@ -21,6 +21,7 @@
 
 namespace llvm {
 
+struct BasicBlockInfo;
 using BBInfoVector = SmallVectorImpl<BasicBlockInfo>;
 
 /// UnknownPadding - Return the worst case padding that could result from