add nsis installer target for mingw32

misc/nsis/Makefile

@@ -0,0 +1,15 @@
+VERSION=1.35_SVN
+RELEASE=0
+
+all: ioquake3-$(VERSION)-$(RELEASE).x86.exe
+
+ioquake3.nsi: ioquake3.nsi.in
+	sed 's/XXXVERSIONXXX/$(VERSION)/;s/XXXRELEASEXXX/$(RELEASE)/' < $< > $@
+
+ioquake3-$(VERSION)-$(RELEASE).x86.exe: ioquake3.nsi
+	makensis ioquake3.nsi
+
+clean:
+	rm -rf *.exe ioquake3.nsi
+
+.PHONY: all clean