nav_types: make btni_t not packed

The use of bitfields of 10 bits makes the use of unsigned char impossible. That means the compiler might use more bits than expected for the 4*12 bits. This is the case with MS-compatible compilers. We cannot guarantee that the btin_t will use the same 10 octets as used in the binary blob.

In the end btin_t is not read as a packed structure but bit by bit in navRead_PCI().

This is breaking the ABI. So while we're at it we remove the packing (and trailing zeros) of structures that are not read as packed structures. They were not read as packed structures when libdvdread was split from libdvdnav but the packed attribute was kept.

mentioned in merge request vlc!2400 (merged)

mentioned in merge request vlc!2402 (merged)

mentioned in commit robUx4/vlc@5c236278

mentioned in merge request vlc!2416 (merged)

mentioned in merge request libdvdnav!51 (closed)

libdvdnav!51 (closed) is a lighter fix for this issue on Windows as it doesn't involve ABI changes other than on Windows.

changed title from nav_types: make btin_t not packed to nav_types: make btni_t not packed

Please do the minimal changes required for llvm.

This minimal fix is libdvdnav!51 (closed). The proper/future-proof/safe fix is this MR.

mentioned in commit robUx4/vlc@1a082006

mentioned in commit robUx4/vlc@94db2f10

mentioned in commit robUx4/vlc@1964f384

mentioned in merge request vlc!2457 (merged)

mentioned in commit robUx4/vlc@49a27d65