Coccinelle: Cleanup the setting of the FLAGS and OPTIONS variables

The FLAGS variable is factorized independently of the ONLINE mode.
The OPTIONS variable is now based on LINUXINCLUDE and explicit
includes are thus removed.

The format of the -I option differs between gcc and spatch.
The COCCIINCLUDE is used to adapt the format. This rewritting
needs bash.

Signed-off-by: Nicolas Palix <nicolas.palix@imag.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>