ARM IAS: support #:{lower,upper}16: for GNU compatibility

The GNU assembler supports prefixing the expression with a '#' to indiciate that
the value that is being moved is infact a constant.  This improves the
compatibility of the integrated assembler's parser for this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198916 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/AsmParser/ARMAsmParser.cpp

@@ -4813,6 +4813,10 @@ bool ARMAsmParser::parseOperand(SmallVectorImpl<MCParsedAsmOperand*> &Operands,
 bool ARMAsmParser::parsePrefix(ARMMCExpr::VariantKind &RefKind) {
   RefKind = ARMMCExpr::VK_ARM_None;
 
+  // consume an optional '#' (GNU compatibility)
+  if (getLexer().is(AsmToken::Hash))
+    Parser.Lex();
+
   // :lower16: and :upper16: modifiers
   assert(getLexer().is(AsmToken::Colon) && "expected a :");
   Parser.Lex(); // Eat ':'