Fix a segfault in lash, hush, and cmdedit.  Each of these used
xgetcwd, but did not check the return for a NULL, and then continued
to call strlen on the NULL when the cwd had been removed from under it.
 -Erik
diff --git a/Makefile b/Makefile
index 7ab060f..cbaf057 100644
--- a/Makefile
+++ b/Makefile
@@ -259,7 +259,7 @@
 LIBBB_MSRC=libbb/messages.c
 LIBBB_MESSAGES= full_version name_too_long omitting_directory not_a_directory \
 memory_exhausted invalid_date invalid_option io_error dash_dash_help \
-write_error too_few_args name_longer_than_foo
+write_error too_few_args name_longer_than_foo unknown
 LIBBB_MOBJ=$(patsubst %,$(LIBBB)/%.o, $(LIBBB_MESSAGES))