nx-X11/programs/Xserver/hw/nxagent/Display.c: use new ReconnectTolerance nxagentOption value in nxagentCheckForPixmapFormatsCompatibility() and modify behavior based on this value.

Recognized values:
  - Strict means that the number of internal and
    external pixmap formats must match exactly and
    every internal pixmap format must be available
    in the external pixmap format array.
  - Safe means that the number of pixmap formats might
    diverge, but all internal pixmap formats must
    also be included in the external pixmap formats
    array. This is recommended, because it allows
    clients with more pixmap formats to still connect,
    but not lose functionality.
  - Risky means that the internal pixmap formats array
    is allowed to be smaller than the external pixmap
    formats array, but at least one pixmap format must
    be included in both. This is potentially unsafe.
  - Bypass or higher means that all of these checks are
    essentially deactivated. This is a very bad idea.

Note that the default ReconnectTolerance value is still Strict.

Also, the return value of this function is currently not used or passed through
to other functions at all. An upcoming commit will change this behavior and
actually enable the checks.