[CM] possible bug in hook invocation

[Woody Douglass]

Bill et all,

I'm currently trying to debug a peculiar issue -- i create a hook by
calling `(make-hook 'samples)`, assign to it's `hook-functions` to a
list of lambdas (in scheme), and then try to invoke the hook from C
with `s7_call(s, hook, s7_cons(s, samples_list, s7_nil(s));`

sometimes, when the hook is invoked, i get a segfault in
`op_safe_closure_p_a_1` in s7.c

is a lambda created in scheme automatically a "safe closure"? i've been
trying to make sure i'm not being bitten by the GC, but I haven't found
evidence of that yet

Thanks for any advice,
Woody Douglass