Fix exception when parsing tests.pro

The ParseResults may be a nested list of list. Now the code doesn't
raise exceptions, but it fails in do_include as includes that doesn't
provide resolved path will fail. Anyway step in the right direction.

Change-Id: Ice44e4c10d221293cc6c1facca30abd5495791be
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

util/cmake/pro2cmake.py

@@ -629,8 +629,18 @@ class QmakeParser:
         Operation = Key('key') + pp.Optional(LC) \
             + Op('operation') + pp.Optional(LC) \
             + Values('value')
-        CallArgs = pp.Optional(LC) + pp.nestedExpr()
+        CallArgs = pp.Optional(LC) + pp.nestedExpr()\
-        CallArgs.setParseAction(lambda x: ' '.join(chain(*x)))
+
+        def parse_call_args(results):
+            out = ''
+            for item in chain(*results):
+                if isinstance(item, str):
+                    out += item
+                else:
+                    out += "(" + parse_call_args(item) + ")"
+            return out
+
+        CallArgs.setParseAction(parse_call_args)
         Load = pp.Keyword('load') + CallArgs('loaded')
         Include = pp.Keyword('include') + CallArgs('included')
         Option = pp.Keyword('option') + CallArgs('option')