Fix crash due to invalid timespec given to pselect

If blinktimeout is set to a value greater than 1000, pselect will
receive a timeout argument with tv_nsec greater than 1E9 (1 sec), and
fail, making st crash. This patch just ensures that the timespec
structure is correctly filled with a value properly decomposed between
tv_sec and tv_nsec.

Reported by JasonWoof on IRC. Thanks!

st.c

@@ -3922,6 +3922,9 @@ run(void) {
 							TIMEDIFF(now,
 								lastblink)));
 					}
+					drawtimeout.tv_sec = \
+					    drawtimeout.tv_nsec / 1E9;
+					drawtimeout.tv_nsec %= (long)1E9;
 				} else {
 					tv = NULL;
 				}