Fix typo in an error string. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258357 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -2537,7 +2537,7 @@ std::error_code BitcodeReader::parseConstants() {
       return error("Malformed block");
     case BitstreamEntry::EndBlock:
       if (NextCstNo != ValueList.size())
-        return error("Invalid ronstant reference");
+        return error("Invalid constant reference");
 
       // Once all the constants have been read, go through and resolve forward
       // references.