[AsmParser][TableGen] Make the generated mnemonic spell checker function a file local static function.

Also only emit in targets that specificially request it. This is required so we don't get an unused static function error.

llvm-svn: 316640
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 6a3dba7..090d4f3 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -9040,7 +9040,7 @@
   return PlainMatchResult;
 }
 
-std::string ARMMnemonicSpellCheck(StringRef S, uint64_t FBS);
+static std::string ARMMnemonicSpellCheck(StringRef S, uint64_t FBS);
 
 static const char *getSubtargetFeatureName(uint64_t Val);
 bool ARMAsmParser::MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
@@ -10120,6 +10120,7 @@
 #define GET_REGISTER_MATCHER
 #define GET_SUBTARGET_FEATURE_NAME
 #define GET_MATCHER_IMPLEMENTATION
+#define GET_MNEMONIC_SPELL_CHECKER
 #include "ARMGenAsmMatcher.inc"
 
 // Some diagnostics need to vary with subtarget features, so they are handled