Upgrade from 1.13.1 to 1.13.2.

<ChangeLog>

*) Change: nginx now returns 200 instead of 416 when a range starting

with 0 is requested from an empty file.

*) Feature: the "add_trailer" directive.

Thanks to Piotr Sikora.

*) Bugfix: nginx could not be built on Cygwin and NetBSD; the bug had

appeared in 1.13.0.

*) Bugfix: nginx could not be built under MSYS2 / MinGW 64-bit.

Thanks to Orgad Shaneh.

*) Bugfix: a segmentation fault might occur in a worker process when

using SSI with many includes and proxy_pass with variables.

*) Bugfix: in the ngx_http_v2_module.

Thanks to Piotr Sikora.

</ChangeLog>