tests/vm: Add capstone to the NetBSD and OpenBSD VMs

The Capstone library that is shipped with NetBSD and OpenBSD works
fine when compiling QEMU, so let's enable this in our build-test
VMs to get a little bit more build-test coverage.

Message-Id: <20220516145823.148450-2-thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/vm/netbsd

@@ -46,7 +46,8 @@ class NetBSDVM(basevm.BaseVM):
         "jpeg",
         "png",
 
-	# libs: ui
+        # libs: ui
+        "capstone",
         "SDL2",
         "gtk3+",
         "libxkbcommon",

tests/vm/openbsd

@@ -48,7 +48,8 @@ class OpenBSDVM(basevm.BaseVM):
         "jpeg",
         "png",
 
-	# libs: ui
+        # libs: ui
+        "capstone",
         "sdl2",
         "gtk+3",
         "libxkbcommon",