After recent failures discovered by travis-ci it should be safe to
have this back on.

rely on h2_errcheck() calls anyway.

it will ever be useful for.

It complains that &pfh_vut is never NULL...

For out-of-tree code that may set up multiple VUTs in a single process,
we don't want the VUT that initialized a PID file to remove it if it
finishes before other VUTs.

A global pseudo-VUT is introduced to keep track of the PID file and
the error callback in order to use them in the atexit(3) callback.

Original test case by Geoff, slightly modified.

Closes #2651

This can happen if a signal is caught after `VUT_Fini` was called, but
at this point we should no longer manipulate the VUT being dismantled.

Original test case by Geoff, slightly modified.

Closes #2650

consequence of 90c4b747:
if cache_varnishd.h is installed, we also need table files
used therein.

This seems to be the de-facto way to handle such cases.
Fixes #2608.

of the file off-limits for VMODs.

Merges #2577

closes #2625

alpine's getopt returns "progname: unrecognized option: A"

I never thought that I'd have to fix a string concatenation problem in
a BusyBox awk program to generate VT100 code in a container, but here we
are:

echo | awk 'END {print "foo" "" ++a, "foo" ++a}'

should output "foo0 foo1", and for all the ?awk I tested, it does,
except for BusyBox awk who thought funny to output "0 foo1", breaking the
teken_state.h file.

... when the constructor has optional arguments

Reported by ingvar