maint: be less strict about executable permissions of tests

maint: be less strict about executable permissions of tests

With "umask 0027" or even "umask 0077", the git clone of coreutils
does not have the executable bit set for 'other' (or 'group).
Therefore, "make syntax-check" would fail.

* cfg.mk (sc_tests_executable): Change the -perm argument of find(1)
to only print the names of the files which are not executable by the
user, rather than insisting on ugo+x (octal 111).