Use g_return_val_if_fail instead of wrong g_return_if_fail
Use g_return_val_if_fail instead of wrong g_return_if_fail

The commit 4b5e6ec2114e1250c81027ebeac9cfe8d059153f introduced a function
returning gboolean, g_return_val_if_fail() should be used instead of
g_return_if_fail().

fgouget/spice-gtk,flexVDI/spice-gtk,fgouget/spice-gtk,flexVDI/spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk