bindings/vala/Makefile.am: Fix vala vapi generation
bindings/vala/Makefile.am: Fix vala vapi generation

Signed-off-by: Javier Jardón <d9e631309e5549cc595b71faddf6ad547c795ffa@gnome.org>

saitoha/vte-sixel,thestinger/vte-ng,thestinger/vte-ng,saitoha/vte-sixel,saitoha/vte-sixel,thestinger/vte-ng