Fix linking vhost-user binaries with with ./configure -static, by
overriding glib-2.0 dependency with configure results.

Fixes: 0df750e9 ("libvhost-user: make it a meson subproject")
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20201215080319.136228-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>