+# - libxml2-2.9.2 [contents of ftp://xmlsoft.org/libxml2/libxml2-2.9.2.tar.gz]
+# - winpthreads-3.3.0 [directory mingw-w64-libraries/winpthreads from http://downloads.sourceforge.net/mingw-w64/mingw-w64/mingw-w64-release/mingw-w64-v3.3.0.tar.bz2]
+# - win-iconv-0.0.6 [contents of https://win-iconv.googlecode.com/files/win-iconv-0.0.6.tar.bz2]