for headers in the compile directory work unsurprisingly. Without
-I-, the search for "foo.h" begins in the directory of the file
that includes it, and the compile directory is only searched because
`-I.' is in ${INCLUDES}.
Removed -I$S/sys from ${INCLUDES}. It was once necessary to find
things like "param.h" in $S/sys. Now <sys/param.h> is found in $S.
e2e0d560a2