Prefix' Darwin systems are single arch, hijack Darwin7 case which assumes this setup

--- a/configure.ac
+++ b/configure.ac
@@ -1860,7 +1860,7 @@
 	if test "$enable_universal" != "no"; then
 		case "$host_os" in
 
-		darwin[[0-7]].*)
+		darwin**)
 			#
 			# Pre-Tiger.  Build only for 32-bit PowerPC; no
 			# need for any special compiler or linker flags.