tests: fix incorrect caps for shmem-invalid-size, shmem-small-size

VIR_TEST_DEBUG=2 ./qemuxml2argvtest generates the following output:

409) QEMU XML-2-ARGV shmem-invalid-size
... Got expected error: unsupported configuration: ivshmem device is not \
	 supported with this QEMU binary
OK
410) QEMU XML-2-ARGV shmem-small-size
... Got expected error: unsupported configuration: ivshmem device is not \
supported with this QEMU binary
OK

We should have:

409) QEMU XML-2-ARGV shmem-invalid-size
... Got expected error: XML error: shmem size must be a power of two
OK
410) QEMU XML-2-ARGV shmem-small-size
... Got expected error: XML error: shmem size must be at least 1 MiB
OK

This commit fixes the issue by providing QEMU_CAPS_DEVICE_IVSHMEM caps
for shmem-invalid-size, shmem-small-size test.
Signed-off-by: NMaxime Leroy <maxime.leroy@6wind.com>

tests/qemuxml2argvtest.c

@@ -1469,8 +1469,10 @@ mymain(void)
     DO_TEST("shmem", QEMU_CAPS_PCIDEVICE,
             QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_IVSHMEM);
     DO_TEST_FAILURE("shmem", NONE);
-    DO_TEST_FAILURE("shmem-invalid-size", NONE);
-    DO_TEST_FAILURE("shmem-small-size", NONE);
+    DO_TEST_FAILURE("shmem-invalid-size", QEMU_CAPS_PCIDEVICE,
+                    QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_IVSHMEM);
+    DO_TEST_FAILURE("shmem-small-size", QEMU_CAPS_PCIDEVICE,
+                    QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_IVSHMEM);
     DO_TEST_PARSE_ERROR("shmem-msi-only", NONE);
 
     virObjectUnref(driver.config);