It is a bad idea to set CONFIG_FILEPOS_64 from outside.
Bcmastroska2 now follows standart _FILE_OFFSET_BITS to determine whether off_t is a 32 bit or 64 bit integer.
This mistake was creating invalid function pointer cast with the bctoolbox's VFS api (who follows the system off_t).

Rename generated config.h to bcmatroska2_config.h as it is public and may clash with other local config.h file in another project.

Rename CMake targets for uniform naming.

- Initialize unintialized variable if no segments

- Use a more generic prototype for other platform that Desktop in Win32

(cherry picked from commit e7ec7592)

Generate RPM specfile only when targeting Linux.

See merge request !1

Do not store the pointer returned by setlocale(), it might be invalidated by another call to setlocale() in an other library.

That prevents ABI mismatch with recent Android NDK.