This ensures we don't end up with a VSL batched record with conflicting
ids, which breaks the -g grouping modes.

Originally it was the plan that the JSON would be gzip'ed in the
VSM, but to avoid exposing VGZ in the API we didn't, but kept the
gzip'ed JSON in the generated VSC code because why not?

Well now we know why not:  It wastes a lot of time for very little space,
in particular if you have many backends.

Provides some relief for: #2513 & #2518

phk probably has this in a global flexelint config

Fixes: #2351

.keys() doesn't produce a list in python3, only an iterable view

fix: #2511

Spotted by ASAN.

VCL_STRANDS is an alternative to VCL_STRING_LIST which uses a
struct instead of varargs.

This means that multiple VCL_STRANDS can be passed to a function,
and string-compare really needed that to not waste workspace.

Add <, >, <=, >= string comparisons while here anyway.

The struct and a const char *[N] array are built on the stack and
they are only valid for the duration of the function call.

Add a new type "STRINGS" which is internal to vcc_expr.c only,
and convert to "STRING" and "STRING_LIST" at the edge of vcc_expr.c
and as necessary inside.  (More to come.)

Various and sundry cleanups along the way.

Otherwise some compilers *cough* GCC *cough* may fail to see that it's
properly written before any read.

it is genereally useful also for vmods

STRING_LIST to STRING for error messages.

Fixes #2510

Submitted by:	klean@github

Give procedures proper data structures and stick the VCL methods into
the symbol table up front and GC a lot of small hacks and workarounds.

Timing out an H/2 session needs to take into account any active streams
being processed.

that VCL_ENUM have canonical pointers.