cocci: split off "--all-includes" from SPATCH_FLAGS

Per the rationale in 7b63ea57500 (Makefile: remove mandatory "spatch" arguments from SPATCH_FLAGS, 2022-07-05) we have certain flags that are truly mandatory, such as "--sp-file" and "--patch .". The "--all-includes" flag is also critical, but per [1] we might want to ad-hoc tweak it occasionally for testing or one-offs. But being unable to set e.g. SPATCH_FLAGS="--verbose-parsing" without breaking how our "spatch" works isn't ideal, i.e. before this we'd need to know about the default include flags, and specify: SPATCH_FLAGS="--all-includes --verbose-parsing". If we were then to change the default include flag (e.g. to "--recursive-includes") in the future any such one-off commands would need to be correspondingly updated. Let's instead leave the SPATCH_FLAGS for the user, while creating a new SPATCH_INCLUDE_FLAGS to allow for ad-hoc testing of the include strategy itself. 1. https://lore.kernel.org/git/20220823095733.58685-1-szeder.dev@gmail.com/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Taylor Blau <me@ttaylorr.com>