(CHECK_STRING_BYTES) [GC_CHECK_STRING_BYTES]: New macro.
(check_sblock, string_bytes) [GC_CHECK_STRING_BYTES]: New functions.
(check_string_bytes) [GC_CHECK_STRING_BYTES]: Add parameter ALL_P.
(allocate_string) [GC_CHECK_STRING_BYTES]: Always check strings in
the current sblock.
(mark_object) [GC_CHECK_STRING_BYTES]: Use CHECK_STRING_BYTES.
(gc_sweep) [GC_CHECK_STRING_BYTES]: Call check_string_bytes
after sweeping strings, and at the end.
(GC_CHECK_STRING_BYTES): Moved to lisp.h.