Unrelated to #2880, fix formatting of this R-string which cannot incl…

…ude any special formatting, such as \n.

src/basic/vx_config/threshold.cc

@@ -114,7 +114,7 @@ if ( !match &&
 
       mlog << Debug(2) << R"(Please replace the deprecated "SCP" and "CDP" )" 
            << R"(threshold types with "SOCP" and "OCDP", respectively, in the ")"
-           << str << R"(" threshold string.\n)";
+           << str << R"(" threshold string.)" << "\n";
 
       print_climo_perc_thresh_log_message = false;