Use const qualifiers with TargetLowering. This eliminates several
const_casts, and it reinforces the design of the Target classes being
immutable.

SelectionDAGISel::IsLegalToFold is now a static member function, because
PIC16 uses it in an unconventional way. There is more room for API
cleanup here.

And PIC16's AsmPrinter no longer uses TargetLowering.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101635 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/CellSPU/SPUTargetMachine.h b/lib/Target/CellSPU/SPUTargetMachine.h
index 9fdcfe9..37e7cd2 100644
--- a/lib/Target/CellSPU/SPUTargetMachine.h
+++ b/lib/Target/CellSPU/SPUTargetMachine.h
@@ -57,8 +57,8 @@
     return NULL;
   }
 
-  virtual       SPUTargetLowering *getTargetLowering() const { 
-   return const_cast<SPUTargetLowering*>(&TLInfo); 
+  virtual const SPUTargetLowering *getTargetLowering() const { 
+   return &TLInfo;
   }
 
   virtual const SPURegisterInfo *getRegisterInfo() const {