test-coroutine: prepare for the next patch

The next patch moves the coroutine argument from first-enter to
creation time.  In this case, coroutine has not been initialized
yet when the coroutine is created, so change to a pointer.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Author: bonzini

tests/test-coroutine.c

@@ -40,15 +40,16 @@ static void test_in_coroutine(void)
 
 static void coroutine_fn verify_self(void *opaque)
 {
-    g_assert(qemu_coroutine_self() == opaque);
+    Coroutine **p_co = opaque;
+    g_assert(qemu_coroutine_self() == *p_co);
 }
 
 static void test_self(void)
 {
     Coroutine *coroutine;
 
     coroutine = qemu_coroutine_create(verify_self);
-    qemu_coroutine_enter(coroutine, coroutine);
+    qemu_coroutine_enter(coroutine, &coroutine);
 }
 
 /*