gl: allow to include GLES/gl.h

https://bugzilla.gnome.org/show_bug.cgi?id=703343
egl/eglglessink: remove since EGLImage and iOS support have been added in glimagesink

https://bugzilla.gnome.org/show_bug.cgi?id=703343
egl: Add libgstegl and eglgles plugin to the CRUFT directories
mpegts: for loop initial declarations are only allowed in C99 mode

Fixes compiler warnings.
mpegts: add linkage descriptor

https://bugzilla.gnome.org/show_bug.cgi?id=727403
mpegts: add parential rating descriptor

https://bugzilla.gnome.org/show_bug.cgi?id=727403
dvb: Minor code style fix
mpegts: add private data specifier descriptor

https://bugzilla.gnome.org/show_bug.cgi?id=727403
mpegts: add data broadcast id descriptor

https://bugzilla.gnome.org/show_bug.cgi?id=727403
mpegts: add frequency list descriptor

https://bugzilla.gnome.org/show_bug.cgi?id=727560
mpegts: add scrambling descriptor

https://bugzilla.gnome.org/show_bug.cgi?id=727560
mpegts: add dvb ca identifier descriptor

https://bugzilla.gnome.org/show_bug.cgi?id=727560
dvbsrc: Don't try to access NULL string

And refactor the pid setting code to be in its own function for clarity

CID #206374
dvbsrc: Don't close a fd that wasn't open

We are handling the failure cases in this block where the open failed

CID #206179
dvbsrc: Handle failure to get statistics from the device

Check the ioctl return value and don't output bogus values.

CID #206016
dvb: Handle socket() failure

CID #206178
dvb/camsession: Don't do operations on unexisting sessions

CID #206114
configure: Detect EGL header presence

Fixes the build for Android, and I suspect for other systems too...
dvb: Fix if() check

introduced by my previous commit :(
mxf: avoid dereferencing NULL mapping data pointer

Also unref buffers on error, as it seems to be done in one, but
not all, error paths.

The NULL pointer part is Coverity 206112

https://bugzilla.gnome.org/show_bug.cgi?id=727889