We introduce two new variables: ABI and IMAKEOPTS
ABI determines the correct ABI to use and is set during bootstrapping
from /etc/compiler.defaults.
IMAKEOPTS are the options passed to imake to allow it to set the right
definitions and find the right paths etc. Use IMAKEOPTS with SunOS, too.
IRIX will always require xpkgwedge, since it's got a bogus X11BASE.
When linking against libXaw, make sure we get the right ABI.
Always check for ${OPSYS} == "IRIX" (and not once for != and once for ==)
Always use "-Wl,-rpath,/path" rather than sometimes "-Wl,-rpath -Wl,/path"
and sometimes "-Wl,-rpath,/path".
