Emma Anholt authored Sep 18, 2017 and Adam Jackson committed Sep 20, 2017

The extension was using the name CARD64 to represent 64-bit values,
with a #define from CARD64 to XSyncValue, a struct with a pair of
32-bit values representing a signed 64-bit value.  This interfered
with protocol headers using CARD64 to try to actually store a
uint64_t.  Now that stdint.h exists, let's just use that here,
instead.

v2: Fix alarm delta changes.
v3: Do the potentially overflowing math as uint and convert to int
    afterward, out of C spec paranoia.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Keith Packard <keithp@keithp.com>