upgraded lua-resty-core to 0.1.18rc4.

win32/win64: upgraded pcre to 8.44.

bumped version to 1.15.8.1.

bugfix: added an openssl patch to fix the parallel build regression i…

…n openssl 1.1.0j.

restydoc: updated the bundled version of the LuaJIT docs to the latest.

formal release 1.13.6.1.

bumped version to 1.11.2.5; also updated tests to reflect recent chan…

…ges.

bugfix: applied nginx's official security fix for an issue in the ran…

…ge filter (CVE-2017-7529).

formal release 1.11.2.3.