vulkan: add vk_x11_strict_image_count option

vulkan: add vk_x11_strict_image_count option

This option strictly allocate the minImageCount given by the
application at swapchain creation.

This works around application that do not deal with the fact that the
implementation allocates more images than the minimum specified.

v2: Add values in default drirc (Bas)

v3: specify engine name/version (Lionel)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111522
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Cc: 19.2 <mesa-stable@lists.freedesktop.org>