Rename do_exit_flag to exit_requested

... and change the type to sig_atomic_t. Also, make it
globally available again (because it is indeed useful in
other parts of the code)

Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Change-Id: Ifd6f0d9145c689ecce0609a2d04b2221f8533181
Reviewed-on: https://review.coreboot.org/c/em100/+/47842
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2 files changed