[BOLT] Fix diagnostic message output

[maksfb]

Summary

Add missing EOL.

bolt/lib/Rewrite/RewriteInstance.cpp

for (auto ISym = SortedFileSymbols.begin(); ISym != SortedSymbolsEnd;
     if (ColdFragment.match(SymName)) {
       static bool PrintedWarning = false;
       if (!PrintedWarning) {
         PrintedWarning = true;
         errs() << "BOLT-WARNING: split function detected on input : "
                << SymName;
         if (BC->HasRelocations)
           errs() << ". The support is limited in relocation mode\n";
+        else
+          errs() << '\n';
       }
       BC->HasSplitFunctions = true;
       BF->IsFragment = true;
     }
 
     if (!AlternativeName.empty())
       BF->addAlternativeName(AlternativeName);