Revert r203488 and r203520.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203687 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/CallingConv.h

@@ -145,10 +145,6 @@ namespace CallingConv {
     X86_CDeclMethod = 80
 
   };
-
-  /// isARMTargetCC - Return true if the specific calling convention is one of
-  /// ARM target specific calling convention.
-  bool isARMTargetCC(ID id);
 } // End CallingConv namespace
 
 } // End llvm namespace