Sprinkle a few VMSWAP_DEFAULT_PLAINTEXT for architectures where we do not
have any spare cpu cycles to waste (encrypted swap still could be
enabled by the admin in /etc/sysctl.conf).

branches: 1.1.2; 1.1.4; 1.1.10; 1.1.82; 1.1.86;
- add m68k/conf/std.m68k, which includes common standard options for m68k,
options EXEC_ELF32, EXEC_SCRIPTS, and CPU_IN_CKSUM for md cpu_in_cksum.c
- make all m68k ports include common arch/m68k/conf/std.m68k
from MD std.${MACHINE}