Fixes #2329

Spotted by coverity.

Spotted by coverity.

Reported by Coverity:

    ID 1406102:  Incorrect expression  (ASSERT_SIDE_EFFECT)
    /bin/varnishtest/vtc_http2.c: 852 in receive_frame()
    846                         s->wf = 0;
    847                         AZ(pthread_cond_signal(&s->cond));
    848                 }
    849                 continue;
    850         }
    851         AZ(pthread_mutex_unlock(&hp->mtx));
    >>> CID 1406102:  Incorrect expression  (ASSERT_SIDE_EFFECT)
    >>> Argument "vtc_error" of assert() has a side effect because the
    >>> variable is volatile.  The containing function might work
    >>> differently in a non-debug build.
    852         assert(vtc_error || vsb == NULL);
    853         return (NULL);
    854 }
    855
    856 #define STRTOU32(n, ss, p, v, c)                             \
    857         do {                                                 \

Although I'm not sure how relevant it is since assert() from vas.h
doesn't remove side effects when no-op'd.

The name idle_send_timeout does not seem to describe well where the timeout
applies (individual write()/writev() calls for arbitraty amounts of data).

The fact that the explanation is complicated might be an indication that a
different timeout implementation be more appropriate.

HTTP2 should probably implement send_timeout somewhen.

Spotted by Coverity:

    /lib/libvgz/deflate.c: 605 in deflateParams()
    599     }
    600     if (s->level != level) {
    601         if (s->level == 0 && s->matches != 0) {
    602             if (s->matches == 1)
    603                 slide_hash(s);
    604             else
    >>> CID 1401053:  Control flow issues  (NESTING_INDENT_MISMATCH)
    >>> The macro on this line expands into multiple statements, only
    >>> the first of which is nested within the preceding parent while
    >>> the rest are not.
    605                 CLEAR_HASH(s);
    606             s->matches = 0;
    607         }
    608         s->level = level;
    609         s->max_lazy_match   = configuration_table[level].max_lazy;
    610         s->good_match       = configuration_table[level].good_length;

We now process the inclusive globs first, and then the exclusive
ones.  The former are accumulative, while the latter will filter
the output from the first.

Discussed in detail with and final diff from @mbgrydeland.
Tests tweaking by yours truly.

Fixes #2320.

If an object has OA_VARY, we should succeed in getting it.

This might help to narrow down #2319

A variable length attribute (OA_HEADERS and OA_VARY) are allowed to be
overwritten if the new data has the exact same length as the previous
data. To check this, its length is recorded. But the length wasn't
recorded, and the code would treat it as a new attribute.

The reason this hasn't caused issues is that the code looking at
OA_HEADERS and OA_VARY ignores the stored attribute length, and that
these aren't ever overwritten.

Retune SHA2 code for improved performance on CPUs with more ILP and
a preference for memory load instructions over large code footprints
with embedded immediate variables.

On amd64 CPUs from 2007-2008 there is not a significant change, but
amd64 CPUs from 2009-2010 get roughly 10% more throughput with this
code; amd64 CPUs from 2011-2012 get roughly 15% more throughput; and
AMD64 CPUs from 2013-2015 get 20-25% more throughput.  The Raspberry
Pi 2 increases its throughput by 6-8%.

Sponsored by:   Tarsnap Backup Inc.

The generated code needs a larger stack when optimizations are
disabled, i.e. with --enable-debugging-symbols.