Suppress a clang 12 warning about "suspicious concatenation".

Suppress a clang 12 warning about "suspicious concatenation".

My clang doesn't like it when we write code like this:

    char *list[] = {
       "abc",
       "def",
       "ghi"
       "jkl"
    }

It wonders whether we meant to put a comma between "ghi" and "jkl"
or not, and gives a warning.

To suppress this warning (since in this case, we did mean to omit
the comma), we just wrap the two strings in parentheses.

Closes #40426; bugfix on 0.4.0.4-rc.