older-nginx-versions: Add NGX_CONF_MULTI to ps_command flags.

Older nginx versions don't allow 'pagespeed' configuration
directives to appear in blocks other then http{} without it.

Fixes https://github.com/pagespeed/ngx_pagespeed/issues/786
script-filters: Allow using script variables in Enable/DisableFilters

To support a non-evil way (if-in-location) of tuning SPDY specific
configuration, allow scripting of Enable/DisableFilters in nginx.conf
Check type of resolver_ctx->addrs.

Check the type of resolver_ctx->addrs and make sure that it is
ngx_addr_t* instead of in_addr_t*. addresses issue #839
Merge pull request #841 from pagespeed/crowell-tengine-stable-support

Check type of resolver_ctx->addrs.
Merge pull request #798 from pagespeed/oschaaf-trunk-tracking-conf-multi

older-nginx-versions: Add NGX_CONF_MULTI to ps_command flags.
NGX_CONF_MULTI: Typo

Fix accidental double pipe symbol.

Fixes https://github.com/pagespeed/ngx_pagespeed/issues/843
Merge pull request #846 from pagespeed/oschaaf-trunk-tracking-conf-multi-typo

NGX_CONF_MULTI: Typo
Merge pull request #822 from pagespeed/oschaaf-trunk-tracking-script-filters

script-filters: Allow using script variables in Enable/DisableFilters
testing: allow the prioritize_critical_css post test to fail
script-filters: Add a test for modifying filters via script variables

As requested via https://github.com/pagespeed/ngx_pagespeed/pull/822
Merge pull request #849 from pagespeed/jefftk-prioritize-critical-css-test

testing: allow the prioritize_critical_css post test to fail
Merge pull request #850 from pagespeed/oschaaf-trunk-tracking-script-filters-test

script-filters: Add a test for modifying filters via script variables
Fix error with url cache purging test.  Followup to #850.
Merge pull request #851 from pagespeed/jefftk-fix-url-purging

Fix error with url cache purging test.  Followup to #850.
Rework parallization separation
Merge pull request #855 from pagespeed/jefftk-fix-tempdir

Rework parallization separation
Move duplicate tests from the nginx-specific system test to system/system_test

As system/system_test.sh is in the mod_pagespeed repo, this is just a bunch of
deletes.
Merge pull request #852 from pagespeed/jefftk-move-tests-to-system

Move duplicate tests from the nginx-specific system test to system
Upstream the change to check_failures_and_exit, moving it to mod_pagespeed
Merge pull request #857 from pagespeed/jefftk-upstream-check-failure-function

Upstream the change to check_failures_and_exit, moving it to mod_pagespeed