Update from 1.5.1 to 1.5.2.
Temporary ignore third-party syslog support.
*) Feature: now several "error_log" directives can be used.
*) Bugfix: the $r->header_in() embedded perl method did not return value
of the "Cookie" and "X-Forwarded-For" request header lines; the bug
had appeared in 1.3.14.
*) Bugfix: in the ngx_http_spdy_module.
Thanks to Jim Radford.
*) Bugfix: nginx could not be built on Linux with x32 ABI.
Thanks to Serguei Ivantsov.