fixed speedup for missing tapes when auto-playing/testing/uploading

fixed speedup for missing tapes when auto-playing/testing/uploading

The tape check to speed up automatic tape playing/testing/uploading
for missing tapes (by skipping loading the level) was buggy, because
non-standard solution tapes (like Supaplex tapes that are part of the
level file) were also wrongly detected as "missing" (and therefore
skipped).

This problem was fixed by only checking for missing private tapes, but
not doing the check if handling solution tapes or explicitly specified
tape files.

This fixes commits e11fa67d and b4d5ee2c.