Turn on pubnames by default on linux.

Until gdb supports the new accelerator tables we should add the
pubnames section so that gdb_index can be generated from gold
at link time. On darwin we already emit the accelerator tables
and so don't need to worry about pubnames.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188708 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -434,6 +434,7 @@ class DwarfDebug {
   // DWARF5 Experimental Options
   bool HasDwarfAccelTables;
   bool HasSplitDwarf;
+  bool HasDwarfPubNames;
 
   unsigned DwarfVersion;