Tests: Fix newline matching in several RunCMake.* cases

The RunCMake infrastructure's `*-stdout.txt` expected output files
interpret `\n` as a `\` and `n` rather than a newline.  Use a literal
newline instead.  Otherwise the cases that were trying to match any
configuration name via `[^\n]*` would fail on `RelWithDebInfo` because
it contains the letter `n`.