(perl #132849) try to disable core files when deliberatly segfaulting

(perl #132849) try to disable core files when deliberatly segfaulting

The dist/Storable/stacksize tool probes for recursion limits for
Storable, in an attempt to prevent stack overflows, and causes
segfaults when the probes exceed the available stack size.

This was leaving a core file for each failure (whether that ended
up as a single file or one for each segfault depended on the
system settings).

Try to probe for the ulimit -c option and if it doesn't cause an
error, prefix the command used to probe for recursion limits.

Ideally I could use setrlimit() for this, but we don't expose it in
core, nor in POSIX.pm, and adding it wouldn't help for the older
perls that Storable needs to build for.