(cherry picked from commit 32d7c195)

(cherry picked from commit 887736bc)

(cherry picked from commit 1b8c2589)

(cherry picked from commit 3a1bb933)

(cherry picked from commit dfb49097)

(cherry picked from commit d7bb1025)

(cherry picked from commit 4722b2d0)

(cherry picked from commit f100cdb6)

This ensures that test data is not dependent on the order the tests are
executed in.

(cherry picked from commit 1245cd17)

(cherry picked from commit 793bdaad)

(cherry picked from commit 370d1ff2)

(cherry picked from commit 47cee871)

(cherry picked from commit b70e27e0)

(cherry picked from commit d1b882dd)

(cherry picked from commit b2489d31)

(cherry picked from commit 7719da95)

(cherry picked from commit 85576598)

Backport of mariusmuja/flann@f8ca6df3.

https://bugs.launchpad.net/ubuntu/+source/gcc-4.9/+bug/1474304

A define was forgotten for the codecs and there was a typo for
another.

(cherry picked from commit f052b0bc)

Conflicts:
	modules/videoio/src/ffmpeg_codecs.hpp

(cherry picked from commit 30912b49)

Conflicts:
	modules/videoio/src/cap_ffmpeg_impl.hpp
	modules/videoio/src/ffmpeg_codecs.hpp

(cherry picked from commit 2b2e3ee9)

Conflicts:
	cmake/OpenCVFindLibsVideo.cmake
	modules/videoio/src/cap.cpp
	modules/videoio/src/cap_ffmpeg_impl.hpp
	modules/videoio/src/ffmpeg_codecs.hpp
	modules/videoio/test/test_ffmpeg.cpp