make: fatal error: don't know how to make ./../include/ansidecl.h (bu42). *** Error code 1 (bu21)
Are you building in the srcdir or a separate objdir? Building in the srcdir is supposed to work, but is known to be broken in gcc-4.0.0. So you must build in a separate objdir. E.g.
mkdir objdir
cd objdir
../gcc-4.0.0/configure ...
Are you using GNU make? The gcc makefile requires a recent version of GNU make.
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com
