qemu_capabilities: Put only unique FW images into domcaps

In the domain capabilities XML there are FW image paths printed.
There are two sources for the image paths (in order of
preference):

  1) firmware descriptor files - as returned by
  qemuFirmwareGetSupported()

  2) a compile time list of FW:NRAM pairs which can be overridden
  in qemu.conf

If either of those contains a duplicate FW image path (which is
a valid use case) it is printed twice in the capabilities XML.
While it's technically not a bug, it doesn't look good.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Tested-by: NKashyap Chamarthy <kchamart@redhat.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>

src/qemu/qemu_capabilities.c

@@ -5136,12 +5136,22 @@ virQEMUCapsFillDomainLoaderCaps(virDomainCapsLoaderPtr capsLoader,
 
     for (i = 0; i < nfirmwares; i++) {
         const char *filename = firmwares[i]->name;
+        size_t j;
 
         if (!virFileExists(filename)) {
             VIR_DEBUG("loader filename=%s does not exist", filename);
             continue;
         }
 
+        /* Put only unique FW images onto the list */
+        for (j = 0; j < capsLoader->values.nvalues; j++) {
+            if (STREQ(filename, capsLoader->values.values[j]))
+                break;
+        }
+
+        if (j != capsLoader->values.nvalues)
+            continue;
+
         if (VIR_STRDUP(capsLoader->values.values[capsLoader->values.nvalues],
                        filename) < 0)
             return -1;