The crypt_r() function returns NULL on errors, check it explicitly instead
of assuming errno will remain 0 if there are no errors (per POSIX, the
setting of errno after a successful call to a function is unspecified
unless the description of that function specifies that errno shall not
be modified).

Additionally, dropped unneeded ngx_set_errno(0) and fixed error handling
of memory allocation after normal crypt(), which was inapropriate and
resulted in null pointer dereference on allocation failures.

This includes "debug_connection", upstreams, "proxy_pass", etc.
(ticket #92)

To preserve compatibility, "listen" specified with a domain name
selects the first IPv4 address, if available.  If not available,
the first IPv6 address will be used (ticket #186).

This will result in alphabetical sorting of included files if
the "include" directive with wildcards is used.

Note that the behaviour is now different from that on Windows, where
alphabetical sorting is not guaranteed for FindFirsFile()/FindNextFile()
(used to be alphabetical on NTFS, but not on FAT).

Approved by Igor Sysoev, prodded by many.

Catched by dav_chunked.t on Solaris.  In released versions this might
potentially result in corruption of complex protocol responses if they
were written to disk and there were more distinct buffers than IOV_MAX
in a single write.

if there were more than 512 listening sockets in configuration.

Worker processes are now made aware of their sequential number needed
to select CPU affinity mask.  This replaces a workaround from r4865.

There are reports that call to a signal handler for an exited process
despite waitpid() already called for the process may happen on Linux
as well.

This fixes unwanted/incorrect cpu_affinity use on dead worker processes
respawn.  While this is not ideal, it's expected to be better when previous
situation where multiple processes were spawn with identical CPU affinity
set.

Reported by Charles Chen.