[CM] Possible bug in `member`

[bil at ccrma.Stanford.EDU]

Thanks for the bug report!  This is an inadvertent
shared list -- an over-eager optimizer basically.
I'll have to trace it back to where the optimizer
made its mistake, but in the meantime, change
line 38562 (or thereabouts) in g_member from

y = list_1(sc, args);

to:

y = list_1(sc, copy_proper_list(sc, args));