[processing] add support for longlong fields in spatial join alg (fix #15072)

(cherry picked from commit 87fea73)

Author: alexbruy

python/plugins/processing/algs/qgis/SpatialJoin.py

@@ -113,7 +113,7 @@ def processAlgorithm(self, progress):
         else:
             numFields = {}
             for j in xrange(len(joinFields)):
-                if joinFields[j].type() in [QVariant.Int, QVariant.Double]:
+                if joinFields[j].type() in [QVariant.Int, QVariant.Double, QVariant.LongLong, QVariant.UInt, QVariant.ULongLong]:
                     numFields[j] = []
                     for i in sumList:
                         field = QgsField(i + unicode(joinFields[j].name()), QVariant.Double, '', 24, 16)