contrib/coccinelle: pass include paths to spatch(1)

In the previous commit a new coccinelle rule is added. But neiter `make coccicheck` nor `meson compile coccicheck` did detect a case in builtin/last-modified.c. This case involves the field `scratch` in `struct last_modified`. This field is of type `struct bitmap` and that struct has a member `eword_t *words`. Both are defined in `ewah/ewok.h`. Now, while builtin/last-modified.c does include that header (with the subdir in the #include directive), it seems coccinelle does not process it. So it's unaware of the type of `words` in the bitmap, and it doesn't recognize the rule from previous commit that uses: type T; T *ptr; Fix coccicheck by passing all possible include paths inside the Git project so spatch(1) can find the headers and can determine the types. Signed-off-by: Toon Claes <toon@iotcl.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>