Do not try to execute an empty shell script in core-plugins-one test

The previous code did:
    if `<code that prints nothing on stdout>`; then ...

So the test failed but not for the good reason. The forked shell
printed:
/bin/sh: gmake[2]:: not found

Now, both "Run 'make ...'" tests are simplified and do not rely on
backticks and test(1) anymore. Either the output is inspected or the
exit code is checked.

0 files changed, 0 insertions, 0 deletions