installation information tweaks

[Dave Love]

>>>>> "Jim" == Jim Wilson <wilson@cygnus.com> writes:

 Jim> Looking the GNU make comment, I see that there is a similar
 Jim> comment about 40 lines before that, so I don't think another
 Jim> mention is necessary.

Sorry, I don't know why I didn't find that.

 Jim> "Make sure you have a version of Make that supports the
 Jim> @code{VPATH} feature.  (GNU Make supports it, as do Make
 Jim> versions on most BSD systems.)"

However, supporting VPATH isn't good enough.  For some reason the
other makes which do support it (Sun and SGI, at least) behave
differently from GNU make.  We couldn't find another one which would
build G77 in a different dierctory during alpha testing, but I don't
know if a recent BSD one was tried.  I'd suggest adding a remark that
most VPATH mechanisms aren't compatible with GNU make's.

 Jim> 	* config-lang.in: Remove the messages about possible build
 Jim> 	problems -- now either irrelevant to moved to manual.

 Jim> The rs6000 problem might still affect some people, but not very
 Jim> many, so I guess there is no serious problem if we lose it.

The problem has gone away for egcs, for some reason, though it's
relevant for g77+gcc-2.7.  Presumably it's on the edge of the limit.