added jpeg 9a.

download: http://www.ijg.org/files/jpegsr9a.zip
patched llvm to make llvm-config report the correct library names on Windows.
added .gitignore.
added libtiff 4.0.3.

download: http://download.osgeo.org/libtiff/tiff-4.0.3.zip
renamed 3rdparty/jpeg-9a/ to 3rdparty/jpeg/.