Use a variable for product name in launcher messages

This fixes almost everything, there are still a couple of blazerc messages.

--
MOS_MIGRATED_REVID=88846240
diff --git a/src/main/cpp/blaze_startup_options_common.cc b/src/main/cpp/blaze_startup_options_common.cc
index 957546c..1620ace 100644
--- a/src/main/cpp/blaze_startup_options_common.cc
+++ b/src/main/cpp/blaze_startup_options_common.cc
@@ -211,10 +211,10 @@
       return process_extra_arg_exit_code;
     }
     if (!extra_argument_processed) {
-      blaze_util::StringPrintf(error,
-          "Unknown Blaze startup option: '%s'.\n"
+      blaze_util::StringPrintf(
+          error, "Unknown %s startup option: '%s'.\n"
           "  For more info, run 'blaze help startup_options'.",
-          arg);
+          GetProductName().c_str(), arg);
       return blaze_exit_code::BAD_ARGV;
     }
   }