[CodeGen] Use LLVM_ATTRIBUTE_UNUSED instead of LLVM_DUMP_METHOD on a raw_ostream operator<<.

LLVM_DUMP_METHOD includes ATTRIBUTE_NOINLINE. operator<< isn't
what we normally consider a dump method so it should be ok to inline.

This fixes a warning from gcc that some other declaration for some
other class was inline but this one is noinline. Seems like a bogus
warning from gcc really.

Author: topperc

llvm/lib/CodeGen/ScheduleDAGInstrs.cpp

@@ -1522,7 +1522,7 @@ LLVM_DUMP_METHOD void ILPValue::dump() const {
 
 namespace llvm {
 
-LLVM_DUMP_METHOD
+LLVM_ATTRIBUTE_UNUSED
 raw_ostream &operator<<(raw_ostream &OS, const ILPValue &Val) {
   Val.print(OS);
   return OS;