debugutils: Properly calculate the difference with unsigned types

tests.c:161:16: error: taking the absolute value of unsigned type
      'unsigned long' has no effect [-Werror,-Wabsolute-value]
    t->diff += labs (GST_BUFFER_TIMESTAMP (buffer) - t->expected);
goom: Use fabs() instead of abs() to calculate the floating point absolute value

tentacle3d.c:268:7: error: using integer absolute value function 'abs' when
      argument is of floating point type [-Werror,-Wabsolute-value]
  if (abs (tmp - fx_data->rot) > abs (tmp - (fx_data->rot + 2.0 * G_PI))) {
      ^
v4l2bufferpool: Explicitly cast enum "subtype" to its "supertype"

gstv4l2bufferpool.c:608:18: error: implicit conversion from enumeration type
      'enum _GstV4l2BufferPoolAcquireFlags' to different enumeration type
      'GstBufferPoolAcquireFlags' [-Werror,-Wenum-conversion]
  params.flags = GST_V4L2_POOL_ACQUIRE_FLAG_RESURECT;
               ~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
vp9enc: Don't dereference NULL checks

CID #1197703
vp8enc: Don't dereference NULL variable

CID #1139838
Automatic update of common submodule

From 211fa5f to 1f5d3c3
Update .po files
Release 1.3.2
Back to development
ximagesrc: Fix ximage leaks when buffer has more then one ximage

From time to time, when the image_pool list has more then 1 element
and I suppose at start, all but 1 pooled ximage are leaked. This is
due to broken algorithm in gst_ximagesink_src_ximage_get(). There was
also a risk of use after free for the case where the ximage size has
changed.

https://bugzilla.gnome.org/show_bug.cgi?id=728502
qtdemux: add tag mappings for _swr, _mak and _mod tags

swr -> Application name
mak -> device manufacturer
mod -> device model
v4l2bufferpool: Port to bufferpool flush_start/stop method
v4l2object: Don't leak config structure
v4l2allocator: Return a GstFlowReturn instead of boolean in alloc
v4l2allocator: Reset count when stopped
v4l2allocator: Add debug assert to detect calls in the wrong state
v4l2bufferpool: Add a trace when _start() is called
v4l2videodec: Fix handle_frame error handling
v4l2bufferpool: Improve debugging

No need to use obj->element, the pool now have a significant name. Also don't
warn if flushing.
v4l2videodec: Fix use of atomic value