* g10.c (main): Add --require-secmem/--no-require-secmem to cause gpg to
exit if it cannot lock memory.  Also remove --nrsign-key and --nrlsign-key
since this can better be done via --edit-key.
* secmem.c (secmem_init): Return a flag to indicate whether we got the
lock.
* memory.h: Return a flag to indicate whether we got the lock.