CodeGen: use # as the comment leader for ARC marker

Use # as the comment leader for AArch64 auto-release elision marker.
This is to keep it in sync with the value used in swift.  When building
libdispatch for Linux AArch64, the auto-release elision marker was
emitted.  However, ELF uses # as the comment leader while MachO accepts
both ; and #.  Use the common marker for it instead.

llvm-svn: 294877
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 19b63ce..82f412f 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -4835,7 +4835,7 @@
       : TargetCodeGenInfo(new AArch64ABIInfo(CGT, Kind)) {}
 
   StringRef getARCRetainAutoreleasedReturnValueMarker() const override {
-    return "mov\tfp, fp\t\t; marker for objc_retainAutoreleaseReturnValue";
+    return "mov\tfp, fp\t\t# marker for objc_retainAutoreleaseReturnValue";
   }
 
   int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const override {