Patch #553678: Cygwin Makefile.pre.in vestige patch

This patch removes a vestige part of the Cygwin make rules
that didn't quite make it over during the flattening of the
Makefiles. In its current form, it creates a def file but
incorrectly calls it libpython$(VERSION).dll.a which
immediately gets overwritten by the next command.
Obviously, this is useless. It appears, it was useless
in the old nested Makefile structure too. :,)
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 57848dc..ad11ff8 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -354,7 +354,6 @@
 
 # This rule builds the Cygwin Python DLL
 libpython$(VERSION).dll.a: $(LIBRARY_OBJS)
-	dlltool --export-all --output-def $@ $^
 	$(LDSHARED) -Wl,--out-implib=$@ -o $(DLLLIBRARY) $^ \
 		$(LIBS) $(MODLIBS) $(SYSLIBS)