Remove some 'const' specifiers that do nothing but prevent moving the argument.

Found by clang-tidy's misc-move-const-arg. While there drop some
obsolete c_str() calls.

llvm-svn: 271181

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -3863,7 +3863,7 @@ std::error_code BitcodeReader::parseModule(uint64_t ResumeBit,
       if (Record.size() > 8 && Record[8]) {
         if (Record[8]-1 >= GCTable.size())
           return error("Invalid ID");
-        Func->setGC(GCTable[Record[8]-1].c_str());
+        Func->setGC(GCTable[Record[8] - 1]);
       }
       bool UnnamedAddr = false;
       if (Record.size() > 9)