gvfs: add missing libgudev to DEPENDS

It requires libgudev, and libgudev requires udev.
While systemd enabled, there is a build failure:
...
$ bitbake systemd -ccleansstate
$ bitbake gvfs -ccleansstate
$ bitbake gvfs
|x86_64-wrs-linux-libtool:   error: cannot find the library
'.../tmp/sysroots/intel-x86-64/usr/lib64/libudev.la' or
unhandled argument '=/usr/lib64/libudev.la'
...

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>