perl: replace 910-miniperl-needs-inc-dot.patch with smaller scope fix

perl: replace 910-miniperl-needs-inc-dot.patch with smaller scope fix

The patch was first introduced in commit 4a94479f9652 ("perl: update to
5.26.1") to fix the target build when the host perl has
default_inc_excludes_dot enabled. It just added back the `-I`. to every
call of miniperl; this solution is questionable however, as it adds `.` to
the beginning of the search path, not as a final fallback like perl did
before default_inc_excludes_dot (and like miniperl does).

It is also not necessary - only two scripts, write_buildcustomize.pl and
configpm, expect to be able to include a file from `.` (in both cases a
file the script just generated). Just fix the two scripts instead.

Signed-off-by: Matthias Schiffer <redacted>