Get rid of call to StringRef::substr that's never used.

[jlebar]

Summary

substr doesn't modify the string, so this line has no effect.

[majnemer]

LGTM

lib/Support/CommandLine.cpp

if (Handler->getMiscFlags() & CommaSeparated) {
     StringRef::size_type Pos = Val.find(',');
 
     while (Pos != StringRef::npos) {
       // Process the portion before the comma.
       if (Handler->addOccurrence(pos, ArgName, Val.substr(0, Pos), MultiArg))
         return true;
       // Erase the portion before the comma, AND the comma.
       Val = Val.substr(Pos + 1);
-      Value.substr(Pos + 1); // Increment the original value pointer as well.
       // Check for another comma.
       Pos = Val.find(',');
     }
 
     Value = Val;
   }
 
   return Handler->addOccurrence(pos, ArgName, Value, MultiArg);