... after the changes in a80c4f14d2ec046a307a4a041d7647377a7a9a4c

At least for now, we need the vcc private interface because of the
nature of the problem we are solving with this vmod.

This allows for builds against Varnish trunk or any numbered
version; but it doesn't check for a minimum version. In branch 6.0,
we have VARNISH_PREREQ([6.0.0]), which can check against numbered
versions, but fails for Varnish trunk.

ref: 0c74d1b99f1f43fc99725fe14322760afa7858ee

Makes it possible to see the varnishtest command invoked by check,
so as to use it to test individual vtc's.

These are formatted as for VCC_PrintCName() in libvcc.

Only free elements of the VCL table if it is not NULL, and then
don't forget to free the array.