Use StringRef instead of `const char *`.

I don't think there's a need to use `const char *`. In most (probably all?)
cases, we need a length of a name later, so discarding a length will
lead to a wasted effort.

Differential Revision: https://reviews.llvm.org/D49046

llvm-svn: 336612
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugPubTable.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugPubTable.cpp
index 956a91e..de8b6e5 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugPubTable.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugPubTable.cpp
@@ -37,7 +37,7 @@
       if (DieRef == 0)
         break;
       uint8_t IndexEntryValue = GnuStyle ? PubNames.getU8(&Offset) : 0;
-      const char *Name = PubNames.getCStr(&Offset);
+      StringRef Name = PubNames.getCStrRef(&Offset);
       SetData.Entries.push_back(
           {DieRef, PubIndexEntryDescriptor(IndexEntryValue), Name});
     }