Subzero: Fix symbol name mangling. Make flags global.

src/IceInstMIPS32.cpp

 //===- subzero/src/IceInstMips32.cpp - Mips32 instruction implementation --===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 /// \file
@@ skipping 100 matching lines @@
                            const InstMIPS32Label *Label)
     : InstMIPS32(Func, InstMIPS32::Br, 0, nullptr), TargetTrue(TargetTrue),
       TargetFalse(TargetFalse), Label(Label) {}
 
 InstMIPS32Label::InstMIPS32Label(Cfg *Func, TargetMIPS32 *Target)
     : InstMIPS32(Func, InstMIPS32::Label, 0, nullptr),
       Number(Target->makeNextLabelNumber()) {}
 
 IceString InstMIPS32Label::getName(const Cfg *Func) const {
   if (!BuildDefs::dump())
-    return IceString();
+    return "";
   return ".L" + Func->getFunctionName() + "$local$__" + std::to_string(Number);
 }
 
 void InstMIPS32Label::dump(const Cfg *Func) const {
   if (!BuildDefs::dump())
     return;
   Ostream &Str = Func->getContext()->getStrDump();
   Str << getName(Func) << ":";
 }
 
@@ skipping 313 matching lines @@
   }
 
   Str << "\t";
   getDest()->emit(Func);
   Str << ", ";
   getSrc(0)->emit(Func);
 }
 
 } // end of namespace MIPS32
 } // end of namespace Ice