more depends gc / yacc rules overhaul

okay millert@

be explicit in the lex/yacc dependencies
reluctant okay deraadt@

Rather than invoking fork/execve of dc(1) on a pipe, compile in the dc(1)
code directly and use it as a subfunction. This refactoring allows use of
pledge "stdio rpath proc tty" in the main bc(1) pr

Rather than invoking fork/execve of dc(1) on a pipe, compile in the dc(1)
code directly and use it as a subfunction. This refactoring allows use of
pledge "stdio rpath proc tty" in the main bc(1) process before fork, pledge
"stdio rpath tty" after fork, and fully reduced to "stdio" in the dc(1)
child.

This requires two recent to the kernel code (allowing sigsuspend(),
and kill() self as pid 0).
ok otto

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separate termios.h out from scan.l, both have an ECHO define. Noted by
Joris Giovannangeli.

add editline support; from freebsd. ok deraadt@

Stop installing me(1) and ms(1) source code.
We will soon get rid of groff in base,
so there is no longer any way to use these files with base.
No opposition on tech@.

CLEANFILES no longer needed since this is now done by bsd.*.mk

SRCS should refer to the .l and .c files; spotted by naddy

Install bc(1) USD doc.

ok deraadt@ mickey@ jmc@

Makefile for bc(1).

ok deraadt@