Contribs: add libxml2

contrib/src/libxml2/SHA512SUMS

+cb5d88f95feffde6a805a7583306864ad9cc909e958a1044afc6d5864ec480da545343f25c10bba99be59c2344e98d4cd2dcc8a152407a0ce581a51ce214d6bc  libxml2-2.7.8.tar.gz

contrib/src/libxml2/rules.mak

+# libxml2
+
+LIBXML2_VERSION := 2.7.8
+LIBXML2_URL := http://xmlsoft.org/sources/libxml2-$(LIBXML2_VERSION).tar.gz
+
+PKGS += libxml2
+
+$(TARBALLS)/libxml2-$(LIBXML2_VERSION).tar.gz:
+	$(call download,$(LIBXML2_URL))
+
+.sum-libxml2: libxml2-$(LIBXML2_VERSION).tar.gz
+
+XMLCONF = --with-minimal --with-catalog --with-reader --with-tree --with-push --with-xptr --with-valid --with-xpath --with-xinclude --with-sax1 --without-zlib --without-iconv --without-http --without-ftp  --without-debug --without-docbook --without-regexps --without-python
+
+libxml2: libxml2-$(LIBXML2_VERSION).tar.gz .sum-libxml2
+	$(UNPACK)
+	mv $@-$(LIBXML2_VERSION) $@
+	touch $@
+
+.libxml2: libxml2
+	cd $< && $(HOSTVARS) ./configure $(HOSTCONF) CFLAGS="-DLIBXML_STATIC" $(XMLCONF)
+ifndef HAVE_MACOSX
+	cd $< && $(MAKE) install
+endif
+	touch $@