[XRay] ARM 32-bit no-Thumb support in LLVM

This is a port of XRay to ARM 32-bit, without Thumb support yet. The XRay instrumentation support is moving up to AsmPrinter.
This is one of 3 commits to different repositories of XRay ARM port. The other 2 are:

https://reviews.llvm.org/D23932 (Clang test)
https://reviews.llvm.org/D23933 (compiler-rt)

Differential Revision: https://reviews.llvm.org/D23931

llvm-svn: 281878
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.h b/llvm/lib/Target/ARM/ARMSubtarget.h
index 2c14eb0..6d528b8 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.h
+++ b/llvm/lib/Target/ARM/ARMSubtarget.h
@@ -540,6 +540,8 @@
   }
   bool isTargetAndroid() const { return TargetTriple.isAndroid(); }
 
+  virtual bool isXRaySupported() const override;
+
   bool isAPCS_ABI() const;
   bool isAAPCS_ABI() const;
   bool isAAPCS16_ABI() const;