Since the git hashes were being generate by cmake it would only be
generated if the header file was not present. Simple test:

    $ make aerofc-v1_default
    $ touch a
    $ git add a
    $ git commit -m tmp
    $ make aerofc-v1_default

The file build_aerofc-v1_default/build_git_version.h should have the new
hashes and the correspondent .c/c.pp files should be rebuilt, but they
aren't.  The end result is that checking the version with "ver git" in
the nsh console will point to the wrong commit.

This moves the generation of the header to a separate tool and enforces
the command to be executed every time.

Commander: Indicate overload on the ground only if not transient. Adjust max CPU load to 80%. Indicate overload in air immediatley

leftover after rebase

This is cleanup after rebasing

in particular:
- SW release version (in addition to the git hash)
- OS version (tag + git hash if exists)
- mcu version & revision & UUID
- toolchain version

The uuid can be disabled via parameter, it's enabled by default.

The provided versioning information is the same, except for some additions,
like OS version (which still need to be implemented on NuttX).

_global_pos_sub->update(&_global_pos_time, &global_pos); could return
false and in that case global_pos was not set but still accessed.

This is prevented by checking if timestamp == 0.

boards define BOARD_NAME, so board_name() is not necessary. HW_ARCH was
just a wrapper around board_name().

This patch simplifies to having only one common method px4_board_name().

  Reverted MPU6000_BUS_I2C_INTERNAL1 back to MPU6000_BUS_I2C_INTERNAL
  Ony SPI has multiple device

  1) Ensure if CONFIG_SERIAL_DMA is set that cdcacm uart_ops is initalized
     with correct functions in correct slots.
     This was detected only with PX4 build flags
  2) C&P error from F7 would prevent CONFIG_STM32_SERIALBRK_BSDCOMPAT ifdefed
     code from being included.