Fix EUC ESDB and JIS CS-mapper.  This also fixes an identity transformation
by "cat foo.euc-jp | iconv -f euc-jp -t utf-8 | iconv -f utf-8 -t euc-jp".
Rework the aicasm build machinery so that it gets built along with toolchain
components instead of with the kernel and/or modules.  This ensures that it
gets built with the host compiler, not the compiler in obj/... used to build
the target components (which may be a cross-compiler outputting code for a
different architecture and using header files with types and options set up
for the wrong architecture).

Reviewed by:	imp