ocl: Don't use 'inline' attribute on functions

In C99 'inline' is not a hint to the compiler to inline the function,
it is an attribute that affects the linkage of the function.  'inline'
functions are required to have a definition in a different compiliation
unit, so compilers are free to delete 'inline' functions if they want to.

This issue can be seen in Clang when compiling at -O0.  Clang
will sometimes delete 'inline' functions which creates an invalid
program.

Issue 3746: http://code.opencv.org/issues/3746
fix blobdetector
Fixed MSMF video capture initialization
Fixed assertion warning in MSMF frame grabber
Fixing errors
Merge pull request #3190 from StevenPuttemans:fix_simpleblobdetector
Merge pull request #3244 from tstellarAMD:2.4-ocl-inline-fix-v2
Merge pull request #3251 from a-wi:MSMF_camera_errors
Fix for bug #3469 CV_XADD failing in clang+nvcc combination

Taken from 3f0765523113ae7fc1b300f27dd78c642bb2b6c7
Merge pull request #3255 from bhack:fix_cuda_macosx
Fixed MSMF file capture error while opening the file containing unsupported video stream format
Fixed CMake issue with FFMPEG highgui configuration

Currently, FFMPEG source files are included in highgui project file regardless of CMake WITH_FFMPEG option.
After applying this PR FFMPEG files are included only if WITH_FFMPEG option is enabled.
Use FFMPEG capture only if HAVE_FFMPEG flag is defined.
fixing some wrong CPP prefixes - still old interface
Merge pull request #3262 from StevenPuttemans:fix_window_param
Merge pull request #3261 from a-wi:CMake_FFMPEG_config
Fixed warning during cross compile for ARM
set ffmpeg mutex to NULL on destruction.

The Mutex manager registered with ffmpeg must reset the mutex to NULL after destruction, otherwise ffmpeg will give the invalid mutex to the next mutex manager when it asks it to CREATE a new mutex.
See ffmpeg code: http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/utils.c;h=28c5785398fcf11a3d3c70a8cd09e9df798e2734;hb=HEAD#l3423

Cherry picked from head (file has moved but issue is the same).
Conflicts:
	modules/videoio/src/cap_ffmpeg_impl.hpp
Merge pull request #3260 from a-wi:MSMF_file_error
Merge pull request #3266 from mshabunin:arm_warning