By the way, I can explain why I've been able to build NetBSD all this
time (and why the patch had no effect).
I had added this to the t-netbsd makefile a couple of months ago:
# Omit $(srcdir)/ginclude/stddef.h header file for NETBSD
# Comes from gcc/Makefile.in
USER_H = $(srcdir)/ginclude/float.h \
$(srcdir)/ginclude/iso646.h \
$(srcdir)/ginclude/stdarg.h \
$(srcdir)/ginclude/stdbool.h \
$(srcdir)/ginclude/varargs.h \
$(srcdir)/ginclude/stdfix.h \
$(EXTRA_HEADERS)
I got that from the NetBSD Pkgsrc system used for building earlier gcc versions. They've been building gcc without stddef.h for a long time.
John
