tests: genericxml2xml: Add test case for HTTP based disk

tests/genericxml2xmlindata/generic-disk-network-http.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-i686</emulator>
+    <disk type='network' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source protocol='http' name='test.img'>
+        <host name='example.org'/>
+      </source>
+      <target dev='vda' bus='virtio'/>
+    </disk>
+    <disk type='network' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source protocol='https' name='test2.img'>
+        <host name='example.org'/>
+      </source>
+      <target dev='vdb' bus='virtio'/>
+    </disk>
+    <disk type='network' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source protocol='http' name='test3.img'>
+        <host name='example.org' port='1234'/>
+      </source>
+      <target dev='vdc' bus='virtio'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/genericxml2xmltest.c

@@ -99,6 +99,7 @@ mymain(void)
     DO_TEST("perf");
 
     DO_TEST("vcpus-individual");
+    DO_TEST("disk-network-http");
 
     DO_TEST("cpu-cache-emulate");
     DO_TEST("cpu-cache-passthrough");