Windows related fixes:

*) Fixed segmentation fault with empty config on Windows.
   See here for report:
   http://mailman.nginx.org/pipermail/nginx-ru/2011-September/043288.html

*) Recent SDKs allow to build IPV6 only for Windows XP or above.

*) Fixing conflict with SDK off_t definition.

*) Fix of building by Microsoft Visual C++ 10 compiler.

Move SO_ACCEPTFILTER and TCP_DEFER_ACCEPT checks into configure.

NetBSD 5.0+ has SO_ACCEPTFILTER support merged from FreeBSD, and having
accept filter check in FreeBSD-specific ngx_freebsd_config.h prevents it
from being used on NetBSD.  Therefore move the check into configure (and
do the same for Linux-specific TCP_DEFER_ACCEPT, just to be in line).

error_log related fixes:

*) Complain on invalid log levels.

   Previously only first log level was required to be correct, while
   error_log directive in fact accepts list of levels (e.g. one may
   specify "error_log ... debug_core debug_http;").  This resulted
   in (avoidable) wierd behaviour on missing semicolon after error_log
   directive, e.g.

       error_log /path/to/log info
       index index.php;

   silently skipped index directive and it's arguments (trying to
   interpret them as log levels without checking to be correct).

*) Fixed configuration summary and manpage contents for the special
   --error-log-path=stderr case.

r4106, r4107, r4108, r4113, r4156, r4157:

*) ngx_http_mp4_module.
*) "video/mp4" mime type added.

Solaris related fixes:

*) Detect POSIX semaphores in librt on Solaris (ticket #3).
   Patch by Denis Ivanov.
*) Lower optimization level for Sun Studio before 12.1.
   At least Sun Studio 12 has problems with bit-fields exposed by nginx code
   (caught by test suite).  They seems to be fixed in Sun Studio 12.1.  As a
   workaround use "-fast -xalias_level=any" for older versions, it resolves
   the problem.

Configure: catch up with new Linux version numbering (ticket #5).

Catch up with new Linux version numbering scheme as announced at [1] and
suppress unrecognized versions to actually use default 0.

[1] https://lkml.org/lkml/2011/5/29/204

This configure test must run before auto/make, because it adds library.
auto/unix was placed after auto/make just for historical reasons.

Patch by Denis F. Latypoff

patch by Maxim Dounin