Tiny patch for proof-of-concept cleanup of ARMAsmPrinter::EmitStartOfAsmFile()

Small test for sanity check of resulting ARM .s file.
Tested against -r115129.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115133 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCDirectives.h

@@ -43,6 +43,7 @@ enum MCSymbolAttr {
 };
 
 enum MCAssemblerFlag {
+  MCAF_SyntaxUnified,         ///< .syntax (ARM/ELF)
   MCAF_SubsectionsViaSymbols  ///< .subsections_via_symbols (MachO)
 };