constify the TargetMachine being passed through the Mips subtarget
creation.

llvm-svn: 218169
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.h b/llvm/lib/Target/Mips/MipsSubtarget.h
index 4967e7b..62ffdd2 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.h
+++ b/llvm/lib/Target/Mips/MipsSubtarget.h
@@ -141,7 +141,7 @@
   // as from the command line
   enum {NoOverride, Mips16Override, NoMips16Override} OverrideMode;
 
-  MipsTargetMachine *TM;
+  const MipsTargetMachine *TM;
 
   Triple TargetTriple;
 
@@ -168,7 +168,8 @@
   /// This constructor initializes the data members to match that
   /// of the specified triple.
   MipsSubtarget(const std::string &TT, const std::string &CPU,
-                const std::string &FS, bool little, MipsTargetMachine *TM);
+                const std::string &FS, bool little,
+                const MipsTargetMachine *TM);
 
   /// ParseSubtargetFeatures - Parses features string setting specified
   /// subtarget options.  Definition of function is auto generated by tblgen.