constify the TargetMachine being passed through the Mips subtarget
creation.

llvm-svn: 218169
diff --git a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
index c1bbf61..1bf21cb 100644
--- a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
@@ -35,7 +35,7 @@
                                             "stores to their single precision "
                                             "counterparts"));
 
-MipsSETargetLowering::MipsSETargetLowering(MipsTargetMachine &TM,
+MipsSETargetLowering::MipsSETargetLowering(const MipsTargetMachine &TM,
                                            const MipsSubtarget &STI)
     : MipsTargetLowering(TM, STI) {
   // Set up the register classes
@@ -228,7 +228,7 @@
 }
 
 const MipsTargetLowering *
-llvm::createMipsSETargetLowering(MipsTargetMachine &TM,
+llvm::createMipsSETargetLowering(const MipsTargetMachine &TM,
                                  const MipsSubtarget &STI) {
   return new MipsSETargetLowering(TM, STI);
 }