dahdi: smp_mb_{before,after}_clear_bit -> smp_mb_{before,after}_atomic.

This is needed to compile against upstream Linux 3.18 since commit
"locking: Remove deprecated smp_mb__() barriers" [1].

[1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2e39465abc4b7856a0ea6fcf4f

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>
build_tools/dkms-helper: Use bash to process dkms-helper script.

Looks like there are some bashims in the script. Make this explicit in the
script until they can be taken out.

This fixes failures to run this script on Ubuntu when dash is the default shell.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks@digium.com>