Re: es portability nits

[Paul Haahr <haahr@mv.us.adobe.com>]

> Why have REQUIRE_xxx macros?

because, at least in some of the configurations i've been working in,
some things conflict with each other.  it worked best, that's all.
i also tried to avoid bringing too much into scope, but that hasn't
worked well.

> and just include <unistd.h> if you have it.

i don't have it on my default machine.  and i've seen at least one machine
where /usr/include/unistd.h and /usr/include/sys/types.h causes conflicts
even just using the manufacturer's distributed headers.

> /bin/gcc -g -O -Wall -D__LANGUAGE_C -D__mips -c except.c
>                      ^^^^^^^^^^^^^^^^^^^^^^^ What are these and why are
>                      they in the default CFLAGS line?

a bug.  i shipped things out of a directory i had been building things for
a dec/mips box in and (1) the dec header files require those, (2) the
compiler should declare them, and (3) the configuration of gcc i've been
using doesn't declare them.