mtest2make.py: teach suite name that are just "PROJECT"

A subproject test may be simply in the "PROJECT" suite (such as
"qemu-common" with the following patches)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230302131848.1527460-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed