* Encapsulate video support with compilation variable EXV_ENABLE_VIDEO
* Encapsulate video support with compilation variable EXV_ENABLE_VIDEO: add variable to unit test files
* Encapsulate video support with compilation variable EXV_ENABLE_VIDEO: encapsulate in makefile
* Encapsulate video support with compilation variable EXV_ENABLE_VIDEO: fix PR windows matrix
* Encapsulate video support with compilation variable EXV_ENABLE_VIDEO: activate only for concerned CI tests
* Encapsulate video support with compilation variable EXV_ENABLE_VIDEO: desable for linux release
* Encapsulate video support with compilation variable EXV_ENABLE_VIDEO: add to Fuzz PR
This change adds support for ancient macOS lacking libproc. It also
eliminates a bug where exiv2 could not be built on case-sensitive
file systems (the header file is properly TargetConditionals.h).