dix: Push UpdateCurrentTimeIf down out of the main loop

This was added in:

    commit 312910b4e3
    Author: Chase Douglas <chase.douglas@canonical.com>
    Date:   Wed Apr 18 11:15:40 2012 -0700

        Update currentTime in dispatch loop

Unfortunately this is equivalent to calling GetTimeInMillis() once per
request. In the absolute best case (as on Linux) you're only hitting the
vDSO; on other platforms that's a syscall. Either way it puts a pretty
hard ceiling on request throughput.

Instead, push the call down to the requests that need it; basically,
grab processing and event generation.

Cc: Chase Douglas <chase.douglas@canonical.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Adam Jackson <ajax@redhat.com>

xfixes/cursor.c

@@ -153,6 +153,7 @@ CursorDisplayCursor(DeviceIntPtr pDev, ScreenPtr pScreen, CursorPtr pCursor)
     if (pCursor != CursorCurrent[pDev->id]) {
         CursorEventPtr e;
 
+        UpdateCurrentTimeIf();
         CursorCurrent[pDev->id] = pCursor;
         for (e = cursorEvents; e; e = e->next) {
             if ((e->eventMask & XFixesDisplayCursorNotifyMask)) {