vbox: drop C API definition for release 4.0

Support for compiling this version was dropped in an earlier commit.
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/vbox/Makefile.inc.am

@@ -7,7 +7,6 @@ VBOX_DRIVER_SOURCES = \
 	vbox/vbox_driver.h \
 	vbox/vbox_snapshot_conf.c \
 	vbox/vbox_snapshot_conf.h \
-	vbox/vbox_CAPI_v4_0.h \
 	vbox/vbox_CAPI_v4_1.h \
 	vbox/vbox_CAPI_v4_2.h \
 	vbox/vbox_CAPI_v4_2_20.h \