The changes added enable `lzdoom` to build (and run) on RPI1/RPI0:
- remove the `ARMV8` build option, since it used upstream as a toggle between RPI2 or RPI3 CPU parameters. Since we're passing the platform CPU flags to `gcc` ourselves, they're not really needed and they'll add the wrong options for other ARM platforms
- patch the included LZMA SDK CRC calculation to not assume every ARM platform supports hardware-assistet CRC (i.e. ARMv8). This will fix the build for RPI1/ARMv6 platforms
