geos: Fix geos-config script

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
gdal: Update and fix config script locations

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
gdal: Remove remnants of i686-pc-mingw32

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
libxml2: Symlink config script to standard location

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
gdal: Fix library detection

Also add libxml2 support

Signed-off-by: Timothy Gu <timothygu99@gmail.com>