Use StringRef instead of `const char *`.

[ruiu]

Summary

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.

[grimar]

Looks reasonable, LGTM.

For LLD this seems helps to avoid double find of the name field length:
https://github.com/llvm-mirror/lld/blob/master/ELF/SyntheticSections.cpp#L2219

[JDevlieghere]

LGTM, Thanks!

llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFDebugPubTable.h

struct Entry {
     /// Section offset from the beginning of the compilation unit.
     uint32_t SecOffset;
 
     /// An entry of the various gnu_pub* debug sections.
     dwarf::PubIndexEntryDescriptor Descriptor;
 
     /// The name of the object as given by the DW_AT_name attribute of the
     /// referenced DIE.
-    const char *Name;
+    StringRef Name;
   };
 
   /// Each table consists of sets of variable length entries. Each set describes
   /// the names of global objects and functions, or global types, respectively,
   /// whose definitions are represented by debugging information entries owned
   /// by a single compilation unit.
   struct Set {
     /// The total length of the entries for that set, not including the length

llvm/trunk/lib/DebugInfo/DWARF/DWARFDebugPubTable.cpp

while (PubNames.isValidOffset(Offset)) {
     SetData.Offset = PubNames.getU32(&Offset);
     SetData.Size = PubNames.getU32(&Offset);
 
     while (Offset < Data.size()) {
       uint32_t DieRef = PubNames.getU32(&Offset);
       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});
     }
   }
 }
 
 void DWARFDebugPubTable::dump(raw_ostream &OS) const {
   for (const Set &S : Sets) {