Polish vre.c a bit with respect to memory management and error messages.

Implemented more or less as described in the pcrejit(3) manpage, and
adds some compatibility defines for use with older pre-8.20 libraries
that do not have this functionality.

Fixes: #1080

whitespace with asserts.

and 'import ... from ...'.  Default is on (= no change)

subsequent changes.

Submitted by:	Brad Smith <brad@comstyle.com>

Thanks to Jeff Williams for pointing this out.

Fixes #1122

Fixes #1069

argument to a printflike function.

Moved libdir/varnish to the varnish-libs subpackage where it belongs, and added an ld.so.conf.d fragment file listing libdir/varnish

it would seriously miss the point.

Spotted by:	scoof

n_objsendfile is of course no longer relevant.

That makes n_objwrite pointless.

n_objoverflow was unused.

and threads_failed were not incremented where it should be.

the guard.  This makes 'max' parameter mis-sizing much less problematic.

Spotted by:	scoof

unlock/lock sequence when using critbit, at the expense of a
slightly more ornate API for hashers.

Also make the "noh" argument optional, as originally intended.

Needed to test #1123