Fix build with newer libtool

sigh.
Fix path data number parsing

Previously highly-optimized path data was being garbled during loading.
A patch has been available for over four years.  Fix it.  This is pretty
much the same patch as one submitted by Louis Simard, which I verified
was correct except for two cases where it was using "&=" when "|=" was
intended.

https://bugzilla.gnome.org/show_bug.cgi?id=620923
Do not depend on gio-unix-2.0 as it breaks the MinGW build

Signed-off-by: Richard Hughes <richard@hughsie.com>
rsvg-base.c: Have realpath() Work On Windows

Use _fullpath() on Windows to do the job for realpath() as realpath() does
not exist on Windows.

https://bugzilla.gnome.org/show_bug.cgi?id=710163

Signed-off-by: Richard Hughes <richard@hughsie.com>