BSD build fixes

Visual Studio 2015 fixes

Add the include directories found by cmake to the jack plugin.
This allows for the plugin to compile when the jack headers were
found in a directory that is not normally in the search path of the
compiler (e.g. /usr/local/include)

Add the include directories found by cmake to the v4l2 plugin.
This allows for the plugin to compile when the vl42 headers were
found in a directory that is not normally in the search path of the
compiler (e.g. /usr/local/include)

Add the include directories found by cmake to the pulseaudio plugin.
This allows for the plugin to compile when the pulseaudio headers were
found in a directory that is not normally in the search path of the
compiler (e.g. /usr/local/include)

Add platform specific code to enumerate v4l2 devices on FreeBSD.

Add a list of plugins to cmake that should be build when on FreeBSD.

Link against the compatibility library that provides sysinfo on FreeBSD.

Add cmake module to find the sysinfo compatibility library used on
FreeBSD to emulate that linux specific system call.

Add an additional ifdef to correctly identify FreeBSD as platform when
generating the version string.

Enable the X11 specific members in the gs_window struct when on FreeBSD.

Remove unused include as it is not available on FreeBSD and was
therefore causing a build error.

Add the relevant header file needed on FreeBSD and utilize yet another
ifdef to call pthread_set_name_np as the function name differs from
those on the other platforms.

Add definition on FreeBSD to enable getline in stdio, as it is not
(yet ?) available by default. According to the manpage getline was a
GNU extension but was standardized in POSIX.1-2008.

Always use -fPIC when not on WIN32 or APPLE and not just with gcc.
This allows for building obs with clang on linux and FreeBSD
without explicitly specifying -fPIC as compiler flag to cmake.

This change is purely cosmetic one. _snprintf is still defined in 2015,
but Microsoft may change this in the future.

This change is purely cosmetic one. _snprintf is still defined in 2015,
but Microsoft may change this in the future.

This is related to CRT changes in VS2015. All printf related functions
are now defined inline, which breaks the CMake's link time checking.

Only link to libdl when on Linux. FreeBSD for example has this built
into their libc.

Fix build errors for older versions of the api where
VIDIOC_ENUM_DV_TIMINGS was defined but V4L2_IN_CAP_DV_TIMINGS was not.
I was under the impression that they were added at the same time, but
apparently i was wrong there.

Thanks to kmoore@FreeBSD.org for spotting this on FreeBSD.

On linux, the highlighted text color should always be considered
"active"

The compatibility mode setting wasn't being set when an update occurred.

Instead of letting this area of code crash, check to see if the core is
still active or not, and safely warn and ignore the release if so.

Avoid unnecessarily triggering signals while populating
the ffmpeg formats combo box.

In the settings if you select default container then the
format becomes null.  If null then audio/video codec ids should
not be set on the output format as they will both be
AV_CODEC_ID_NONE causing a context with no streams specified
to be created (error).

linux-v4l2: Replace custom udev callbacks

Use the signal system provided by obs instead of the custom callback
implementation. This reduces the amount of code and complexity.

linux-v4l2: Build fixes for older versions

Add compatibility with older versions of the api by not failing to
build when the VIDIOC_ENUM_DV_TIMINGS is missing. In older versions
of the api there was a different system to get dv-timing presets, which
was replaced by the current enumeration system with Linux 3.4.
This will allow for the plugin to be built against older versions of the
api by disabling the enumeration support, thus reducing the
functionality for some devices.

Improve compatibility with older versions of the api by not requiring
V4L2_CAP_DEVICE_CAPS. If we don't have this, we fall back to using the
capabilities member for the whole device instead of the device_caps
member for the currently selected subdevice. Just like we would do if
the device would not support this.
The new device_caps field was introduced with Linux 3.3.

linux-v4l2: Fix compile error for missing formats