test: add assert()s to fix analyzer warnings

Reduce the analyzer spam a bit by adding some extra asserts.
Since it's test code, we can't have enough of them anyways ;-)

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

test/xi2/protocol-common.c

@@ -56,6 +56,7 @@ fake_init_sprite(DeviceIntPtr dev)
 
     sprite->spriteTraceSize = 10;
     sprite->spriteTrace = calloc(sprite->spriteTraceSize, sizeof(WindowPtr));
+    assert(sprite->spriteTrace);
     sprite->spriteTraceGood = 1;
     sprite->spriteTrace[0] = &root;
     sprite->hot.x = SPRITE_X;