Add missing braces, avoid unnecessary variables.

Noticed by:	fgs

Extensive test cases often lead to a lot of log output,
which at times tripped the following assert:

Assert error in vtc_log_emit(), vtc_log.c line 122:
  Condition(vtclog_left > l) not true.

Double the amount of buffer space allowed to avoid this. Another 256KB
memory use per concurrent running test should be fine.

a VFP function but rather a fetch function calling VFP.

hackishly used.

Requests that end up in the hard "400 Bad Request" handling used to be
logged with incomplete data. (no method, maybe no path, possibly no proto,
and no response status)

Port scans or anything sending a byte and a linefeed would be logged.

Since this is used for logging access to a web site, it makes more sense
to skip these garbage requests.

Fixes:		#1584

Adding a dash if missing the path component does not make sense.

Related bug:	#1584

child process during startup.

Fixes #1407

This prevents SLT_ReqAcct log records with 0 as VXID.

non-fatal.

Fixes: #1414

Fixes: #1466

Fixes #1580

Fixes #1583

Fixes a regression from 33e6fe71

Fixes #1585

Also hide a might-be change until it's really implemented.

Thanks to dridi.boukelmoune@zenika.com for reporting.

This should bring us closer to the exit codes now documented in
varnishd.rst

Fixes #1572 for tools

This should bring us closer to the exit codes now documented in
varnishd.rst

Fixes #1572 for varnishd

Thanks to fgs for reviewing