Use proper linker command for drivers on OpenBSD

This fixes the "Cannot load specified object" / setuid_drv.so: undefined symbol '__guard_local' error that occurs on OpenBSD 5.3. It changes the LD_SHARED variable to use gcc rather than ld. A similar issue is documented here: http://erlang.org/pipermail/erlang-questions/2013-May/073837.html. Tested on OpenBSD 5.3 and FreeBSD 9.
Merge pull request #151 from fjoanis/master

Fix runtime error on OpenBSD 5.3
Try to make the log directory if it doesn't exist

This uses @capflam's patch from https://github.com/klacke/yaws/pull/145
to create the log directory if specified like

    logdir = +path/to/log

in the configuration file.
Merge remote-tracking branch 'MrStaticVoid/yaws-1.96/try-to-create...

...-log-dir-if-specified-in-config'
export yaws:setup_sconf/2 for yapp

The yapp application relies on the yaws:setup_sconf/2 function, but at some
point it was made private to yaws.erl. Export it so yapp works properly
again.
yaws_session_server:print_sessions/0 not working due incorrect message
Merge pull request #155 from mdaguete/session_server_fixes

yaws_session_server:print_sessions/0 not working due incorrect message
When max connections were reached and we attempt to close the socket, it was assumed we had a TCP socket, crashed on SSL sockets
Merge branch 'master' of github.com:klacke/yaws
Incorrect X-Forwarded-For header

When X-Forwarded-For header appears multiple times in a request only the
last value is supplied by yaws_api:headers_x_forwarded_for/1.

RFC 2616 section 4.2 permits multiple headers with the same name as an
equivalent of one header with a comma-separated list of values.

http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2

Pound loadbalancer ( http://www.apsis.ch/pound ) repeats the header.

Change yaws to collect all values for this header and present them as a
single comma-separated list. Add a regression test to test/t2.
Redhat /etc script bug fix by flavio-fernans
Install procedure for FreeBSD wasn't correct
Fix a bug about log rotation. yaws_logger:do_rotate/2 was buggy.
fix a typo: "can be override" => "can be overridden"
Merge pull request #158 from ningzhang/master

fix a typo: "can be override" => "can be overridden"
rel: add Windows scripts
Document rebar use
Merge pull request #148 from tuncer/rel-windows

rel: add Windows scripts
minor yaws.tex edits
Fix option to enable/disable sendfile support in the configure script

Now it is possible to disable sendfile in yaws passing the option
'--disable-senfile' (or '--enable-sendfile=no') to the configure script.
It is also possible to choose between the erlang implementation (the default)
and the yaws implementation.