Further RAWCPP tweakage

Changed translation of backward slashes to forward ones (now in perl.)

alpha-dec-osf1 and alpha-dec-osf3 are now separate configurations.

AC_PROG_GNUCPP: look for (\/|\\)cpp, not (\/|\\\\)cpp

AC_PROG_GNUCPP: translate backward slashes into forward ones.
AC_HAVE_GCC: tweaked sed regexp to catch cygnus gcc snapshot
version strings (i.e., version cygnus-2.7.2...)

reinforce the test for Happy: version 1.4 or later is now *required*

make the RAWCPP test a little more sensible.

remove bogus [ ] in macro for leading underscore test.

Fix the sed string for the gcc check, it was referring to sub-regexps
that didn't exist.

Drop egcs support for gcc test

use * instead of ?, since some seds don't recognise ?, and some also
don't recognise the alternative \{0,1\}. sigh.

remove spurious comma.

Moved feature tests from configure.in to aclocal.m4 and macroified them

fptools specific autoconf macros