Fix XK_NO_MOD and XK_ANY_MOD behavior

XK_NO_MOD match a key without modifiers and XK_ANY_MOD match a key does not
matter what modifiers are pressed to. Like they are mask the best value for
XK_ANY_MOD is all the bits to 1, so the and with any state will be equal to
the state. This also imply that is necessary check the case for XK_NO_MOD
(no modifiers at all) with some modifier in state, and the inverse
(some mask different to XK_ANY_MOD or XK_NO_MOD and no modifiers in state).
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 st.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)