This fixes a diagnostic seen on Ubuntu 10.04 building the examples:

converting a packed 'opd_mode_1_7i77_t' {aka 'struct
opd_mode_1_7i77_struct'} pointer (alignment 1) to a 'u32' {aka 'unsigned int'}
pointer (alignment 4) may result in an unaligned pointer value
[-Werror=address-of-packed-member]

.. this simplifies error checking, and fixes a diagnostic about
comparing signed and unsigned numbers.

.. mostly by hinting to the compiler that they are intended to be
unused.

Enable PCI device enumeration on Compute Module 4

 * The PCI offset may be a 64-bit number like 0x600000000, which needs
   to fit in off_t (for mmap) and board_struct.mem_base
 * off_t is only 64-bits with -D_FILE_OFFSET_BITS=64
   (which is not the default in 2021!!!)
 * This requires the offset to be printed as a uint64_t
 * mmap was not checked for failure

After this change, I can detect a 5i24 plugged into the 1x slot of
a Raspberry Pi Compute Module 4 IO board with 2GB RAM compute module.
That's the only operation I tried.

Make PCI & EPP support conditional

This should fix compilation on aarch64.

Adds Sigma 5 Encoder GTAGs

Add build-essential to install list

Add mesaflash availability info on Fedora

Add CI via github actions

anyio: Add --device AUTO and --device SPI

Fix -Wformat= warnings

Testing performed:  Both found an attached SPI device on a Pi4 e.g.,

    $ ./mesaflash --device auto --addr /dev/spidev0.0 --spi --readhmid | head -1
    unable to set bpw32, fallback to bpw8
    Configuration Name: HOSTMOT2

Mostly, this involves using the "z" length modifier where a sizeof() is involved

hostmot2.c:50:20: warning: ‘hm2_get_pin_secondary_name’ defined but not used [-Wunused-function]
 static const char* hm2_get_pin_secondary_name(hm2_pin_desc_t *pin) {
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~

Allow to pass VERSION string from the build system

Usage:
  $ CFLAGS='-DVERSION=\"version-string\"' make

Signed-off-by: Damian Wrobel <dwrobel@ertelnet.rybnik.pl>