Add a variable to track whether or not we've used a unique section,

e.g. linkonce, to TargetMachine and set it when we've done so
for ELF targets currently. This involved making TargetMachine
non-const in a TLOF use and propagating that change around - I'm
open to other ideas.

This will be used in a future commit to handle emitting debug
information with ranges.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199871 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCTargetObjectFile.cpp

@@ -24,7 +24,7 @@ Initialize(MCContext &Ctx, const TargetMachine &TM) {
 
 const MCSection * PPC64LinuxTargetObjectFile::
 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
-                       Mangler *Mang, const TargetMachine &TM) const {
+                       Mangler *Mang, TargetMachine &TM) const {
 
   const MCSection *DefaultSection = 
     TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang, TM);