selftest/sstatetests: fix up printdiff test to match rework of printdiff logic

selftest/sstatetests: fix up printdiff test to match rework of printdiff logic

Other than the formatting changes, there are two functional ones:

- use perlcross instead of quilt, as quilt is special in the sense
of being excluded from task hash calculcations. perlcross is a full
participant.

- run the full test (local + sstate) for gcc do_preconfiure change
as the necessary fix has been implemented
(sstatesig/find_siginfo: special-case gcc-source when looking in sstate caches)

Note that when several tasks are found to have changed (as is the case
when base do_configure is adjusted), find_siginfo() runs
glob.glob("*/*/*taskname*") against autobuilder sstate cache for each
of those tasks (six or seven times). This is an expensive operation
taking several minutes. I left it in for now, but if it's proven too slow
the test would have to be reduced to checking a specific base recipe
(e.g. zstd-native) rather than a distant image target.

[YOCTO #15289]

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>