dvb-descriptor: Fix comparision

we want to stop if one OR the other is NULL.
dvb-descriptor: Remove unneeded increment
mpegtspacketizer: Remove or move variable assignments

To where they're needed
mpegts: Fix some packetizing bugs

- Length of NIT stream descriptors was not detected correct
- Reserved bits was not set according to EN 300 468, ISO/IEC 13818-1
- Also set output data size if the section was previously packetized

https://bugzilla.gnome.org/show_bug.cgi?id=723892
mpegts: Correctly check for PAT,PMT,CAT,TSDT
mpegts: pmt: Detect descriptor length correct
dvdspu: Remove unused variable
id3tag: Fix uninitialized variable compiler warning

error: variable 'image_type' is used uninitialized whenever
'if' condition is false [-Werror,-Wsometimes-uninitialized]
uvch264src: Fix unitialized variable compiler warnings
vdpau: Fix comparison compiler warning

error: comparison of constant -1 with expression
of type 'const GstVideoFormat' is always false
bz2: Fix typo in header include guards
dfbvideosink: Fix unitialized variable compiler warning
segmentation: Fix integer underflow check

error: comparison of unsigned expression < 0 is
always false [-Werror,-Wtautological-compare]
motioncells: Remove unused private fields
srtpdec: Fix comparison compiler warning

error: comparison of constant -1 with expression of type
'GstSrtpCipherType' is always false
assrender: Fix compiler warning in test

error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
kate: Remove unused variable from unit test
opus: Remove unused variable from unit test
hlsdemux: Use libgcrypt directly instead of going through gnutls

gnutls is also just wrapping gcrypt, but we don't need any of
the TLS related functionality. We just need to be able to decrypt
AES128-CBC.
hlsdemux: Update to non-deprecated GLib thread API