Made appropriate changes to be able to successfully
build C++ files using a Visual C++ build on Windows.

Based on an earlier patch by Kyle Schwarz.

Comments:

-- compat/w32pthreads.h: Made appropriate changes to w32pthreads.h to
   get it to build when it is being included in a C++ file and built
   with Visual C++.  This is mostly a copy of Kyle Schwarz's patch as
   described above.

-- configure:
a) Now calling set_ccvars CXX to cause the various CXX_ variables to
   be setup properly.  For example, with MSVC (Microsoft Visual C++),
   this causes CXX_O to be set to -Fo$@ instead of using the default
   value.  The default value does not work with Visual C++.  This
   change will also have the impact of correcting CXX_O (and possibly
   CXX_C) for other compilers, although this is really only relevant
   for the Intel compiler, in addition to MSVC.
b) Now using cl for the C++ compiler for the MSVC toolchain.  This is
   currently only relevant for building the
   Blackmagic/Decklink-related files under avdevice.
Signed-off-by: Hendrik Leppkes <h.leppkes@gmail.com>

* commit 'd3da8a00':
  omx: Fix allocation check

This commit is a noop, see 16a75304Merged-by: James Almer <jamrial@gmail.com>

* commit 'd32bdadd':
  qsvdec: Fix memory leak on error

This commit is a noop, see b6f80b16Merged-by: James Almer <jamrial@gmail.com>

* commit '6a93b596':
  compat/atomics: add typecasts in atomic_compare_exchange_strong()
Merged-by: James Almer <jamrial@gmail.com>

* commit '2170017a':
  avutil: fix data race in av_get_cpu_flags()

This commit is a noop, see fed50c43Merged-by: James Almer <jamrial@gmail.com>

* commit 'd5759701':
  libkvazaar: Add missing header #includes
Merged-by: James Almer <jamrial@gmail.com>

* commit '892acc70':
  configure: Fail if cuda was enabled and is not available

This commit is a noop. Our CUDA implementation is autodectected.
Merged-by: James Almer <jamrial@gmail.com>

Based on a dependency addition from fbec58da

* commit 'f55c0a64':
  build: Drop stray golomb dependencies
Merged-by: James Almer <jamrial@gmail.com>

* commit 'fbec58da':
  build: Add an internal component for hevc_ps code

This commit is a noop, see 498e9e8eMerged-by: James Almer <jamrial@gmail.com>

* commit 'f912fd76':
  Add missing #includes for standalone spherical-information-related headers
  fate: Add spherical and stereo3d mov tests
  avprobe: Allow specifying multiple stream entries to be shown

This commit is a noop.
Merged-by: James Almer <jamrial@gmail.com>

* commit 'e90137c0':
  mov: Export spherical information
  lavc: Add spherical packet side data API
  lavu: Add AVSphericalMapping type and frame side data

This commit is a noop, see
8f58ecc3
e7a6f8c9
4dcdecf4Merged-by: James Almer <jamrial@gmail.com>

* commit '075acbb6':
  lavu: Add a video section to Doxygen documentation
Merged-by: James Almer <jamrial@gmail.com>

* commit '624aa8ab':
  build: Add missing Makefile entries and ifdefs for QSV hwaccels
Merged-by: James Almer <jamrial@gmail.com>

* commit 'c833c203':
  build: Ensure that the "all" target appears before all Makefile includes
Merged-by: James Almer <jamrial@gmail.com>

* commit '6bd9590b':
  build: Have old H.264/HEVC nvenc encoders select their new counterparts
Merged-by: James Almer <jamrial@gmail.com>

* commit '3e105d08':
  build: Move entries related to building TOOLS to a subdirectory Makefile
Merged-by: James Almer <jamrial@gmail.com>

* commit '4104cc56':
  build: Warn that reconfiguration is necessary if version.h files changed
Merged-by: James Almer <jamrial@gmail.com>

* commit 'f22da2cd':
  configure: add -fPIE instead of -pie to C flags for ThreadSanitizer

This commit is a noop, see 3f55752cMerged-by: James Almer <jamrial@gmail.com>

* commit '404cb747':
  configure: Pass CFLAGS_HEADERS through the right CFLAGS filter
Merged-by: James Almer <jamrial@gmail.com>

* commit '9265364b':
  build: Separate avisynth and avxsynth support

Mostly noop, since it could break linux configure with --enable-avisynth,
and the configure code which was simplified isn't even present in
ffmpeg.

Only merged the cosmetic re-ordering in the Makefile.
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>

Fixes some valgrind warnings.
Reviewed-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

Signed-off-by: Matthew Gregan <kinetik@flim.org>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

The custom callback can cause significant CPU usage on Windows for some large
files with many index entries for some reason.

v2: Move check after parsing options.
Signed-off-by: Marton Balint <cus@passwd.hu>

Signed-off-by: Marton Balint <cus@passwd.hu>

Fixes ticket #6285.
Signed-off-by: Marton Balint <cus@passwd.hu>

~20% faster than AVX.
Signed-off-by: James Almer <jamrial@gmail.com>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Tested-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

Based on the draft spec at http://vfrmaniac.fushizen.eu/contents/opus_in_isobmff.htmlSigned-off-by: Matthew Gregan <kinetik@flim.org>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Based on the draft spec at http://vfrmaniac.fushizen.eu/contents/opus_in_isobmff.html

'-strict -2' is required to create files in this format.
Signed-off-by: Matthew Gregan <kinetik@flim.org>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Fixes use of uninitialized data
Found-by: Thomas Guilbert <tguilbert@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

FF_ARRAY_ELEMS returns a size_t value.

Reviewed-by: ubitux
Signed-off-by: James Almer <jamrial@gmail.com>