[ARM] Some Thumb2ITBlock clean ups. NFC

Some more refactoring, like registering the IT Block pass, less cryptic
variable names, and some simplification of loops.

Differential Revision: https://reviews.llvm.org/D63419

llvm-svn: 363666
diff --git a/llvm/lib/Target/ARM/ARM.h b/llvm/lib/Target/ARM/ARM.h
index 6b3a5fd..f8dd298 100644
--- a/llvm/lib/Target/ARM/ARM.h
+++ b/llvm/lib/Target/ARM/ARM.h
@@ -64,6 +64,7 @@
 void initializeARMConstantIslandsPass(PassRegistry &);
 void initializeARMExpandPseudoPass(PassRegistry &);
 void initializeThumb2SizeReducePass(PassRegistry &);
+void initializeThumb2ITBlockPass(PassRegistry &);
 void initializeMVEVPTBlockPass(PassRegistry &);
 
 } // end namespace llvm