[BOLT][NFCI] Avoid calling registerName() twice

[maksfb]

Summary

Calling registerName() for the same symbol twice, even with a different
size, has no effect other than the lookup overhead. Avoid the
redundancy.

Fixes facebookincubator/BOLT#299

bolt/lib/Rewrite/RewriteInstance.cpp

for (auto ISym = SortedFileSymbols.begin(); ISym != SortedSymbolsEnd;
     }
 
     if (PreviousFunction && PreviousFunction->containsAddress(Address) &&
         PreviousFunction->getAddress() != Address) {
       if (PreviousFunction->isSymbolValidInScope(Symbol, SymbolSize)) {
         if (opts::Verbosity >= 1)
           outs() << "BOLT-INFO: skipping possibly another entry for function "
                  << *PreviousFunction << " : " << UniqueName << '\n';
+        registerName(SymbolSize);
       } else {
         outs() << "BOLT-INFO: using " << UniqueName << " as another entry to "
                << "function " << *PreviousFunction << '\n';
 
         registerName(0);
 
         PreviousFunction->addEntryPointAtOffset(Address -
                                                 PreviousFunction->getAddress());
 
         // Remove the symbol from FileSymRefs so that we can skip it from
         // in the future.
         auto SI = FileSymRefs.find(Address);
         assert(SI != FileSymRefs.end() && "symbol expected to be present");
         assert(SI->second == Symbol && "wrong symbol found");
         FileSymRefs.erase(SI);
       }
-      registerName(SymbolSize);
       continue;
     }
 
     // Checkout for conflicts with function data from FDEs.
     bool IsSimple = true;
     auto FDEI = CFIRdWrt->getFDEs().lower_bound(Address);
     if (FDEI != CFIRdWrt->getFDEs().end()) {
       const dwarf::FDE &FDE = *FDEI->second;