contribs: add dshow

And DxVA2 (why is that in DirectShow?!).
And Direct2D (untested - does not work in older contrib for me).

contrib/src/dshow/SHA512SUMS

+779c4a36a4276c6e18017b898903cdf162c186b2f8de22ac12d995b316fe40d8277374eb88c695e8a760497239ad176a85ea4ecccd0df841283f95ff591997a7  dshow-headers-oss.tar.bz2
+e62868480379fbb7bc7a433836c6884d51e35ca2d903b9b1f0944250a9d87814be087237240ce84e6d173ea84faed5ea834f2b38800e5ac2c2d8365726defb6a  dxva2api.h

contrib/src/dshow/rules.mak

+# DirectX headers
+
+DSHOW_HEADERS_URL := $(CONTRIB_VIDEOLAN)/dshow-headers-oss.tar.bz2
+DXVA2_URL := $(CONTRIB_VIDEOLAN)/dxva2api.h
+D2D_HASH := b1affb70c021200b410eccd377ad5aeef2c5a85b
+D2D_URL := http://nodeload.github.com/2of1/d2d1headers/tarball/master
+# FIXME: ^ D2D not working
+
+ifdef HAVE_WIN32
+PKGS += dshow
+endif
+
+$(TARBALLS)/dshow-headers-oss.tar.bz2:
+	$(DOWNLOAD) $(DSHOW_HEADERS_URL)
+
+$(TARBALLS)/dxva2api.h:
+	$(DOWNLOAD) $(DXVA2_URL)
+
+$(TARBALLS)/d2d_headers.tar.gz:
+	$(DOWNLOAD) $(D2D_URL) -O $@
+
+DSHOW_SOURCES := dshow-headers-oss.tar.bz2 dxva2api.h d2d_headers.tar.gz
+
+.sum-dshow: $(DSHOW_SOURCES:%=$(TARBALLS)/%)
+	$(CHECK_SHA512)
+	touch $@
+
+.dshow: $(DSHOW_SOURCES:%=$(TARBALLS)/%) .sum-dshow
+	mkdir -p -- "$(PREFIX)/include"
+	tar xjf $< -C "$(PREFIX)/include" \
+		--wildcards --no-anchored '*.h' --strip-components=1
+	tar xzf $(TARBALLS)/d2d_headers.tar.gz -C "$(PREFIX)/include" \
+		 --wildcards --no-anchored '*.h' --strip-components=1
+	cp $(TARBALLS)/dxva2api.h "$(PREFIX)/include"
+	touch $@

contrib/tarballs/.gitignore

 *.tar.*
 *.zip
+*.h