kdeui: check aliases from KImageIO::isSupported()

because MIME strings (those from shared-mime-info package for example)
tend to change and exact MIME string match is unreliable

Signed-off-by: Ivailo Monev <xakepa10@gmail.com>

kdeui/util/kimageio.cpp

@@ -100,6 +100,11 @@ bool KImageIO::isSupported(const QString &mimeType, Mode mode)
         if (mimeType == mime) {
             return true;
         }
+        // check aliases
+        const KMimeType::Ptr kmimetype = KMimeType::mimeType(mime);
+        if (kmimetype && kmimetype->is(mimeType)) {
+            return true;
+        }
     }
     return false;
 }