test_virgl_transfer.c: Fix warnings

test_virgl_transfer.c: In function »virgl_test_transfer_1d«:
test_virgl_transfer.c:302:19: warning: comparison between signed
and unsigned integer expressions [-Wsign-
compare]
     for (i = 0; i < sizeof(data); i++)
                   ^
test_virgl_transfer.c:313:19: warning: comparison between signed
and unsigned integer expressions [-Wsign-
compare]
     for (i = 0; i < sizeof(data); i++) {

v2: Correct language of warning messages

Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Signed-off-by: Jakob Bornecrantz <jakob@collabora.com>

tests/test_virgl_transfer.c

@@ -285,7 +285,8 @@ START_TEST(virgl_test_transfer_1d)
     unsigned char data[50*4];
     struct iovec iov = { .iov_base = data, .iov_len = sizeof(data) };
     int niovs = 1;
-    int ret, i;
+    int ret;
+    unsigned i;
     struct virgl_box box;
 
     /* init and create simple 2D resource */