Backend make fails

[Fred Kiefer]

Trying to build the new backend back on mingw fails with the message:
kiefer@XANTHUS ~/GNUstep/core/back
$ /usr/bin/make
GNUmakefile.postamble:31: *** target pattern contains no `%'.  Stop.

This happens independend of the actual backend I am configuring for. 
Commenting out that rule just moves the error to the next rule. If I 
comment out all rules in this file the compilation works.

Cheers
Fred