The lastSetTime value which indicates when the configuration within the
server was last changed was not getting set in the appropriate RandR
requests.
Signed-off-by: Keith Packard <keithp@keithp.com>

Backported from Arctica GH 3.6.x branch.

v2: backport to nx-libs 3.6.x (Ulrich Sibiller)
v3: backport to nx-libs 3.5.0.x (Mihai Moldovan)