C++: Focus the templates extern test on Declarations.

Author: geoffw0

cpp/ql/test/library-tests/templates/extern/elements.expected

@@ -1,7 +1,3 @@
 | extern.cpp:1:20:1:20 | T |
-| extern.cpp:1:20:1:20 | definition of T |
-| extern.cpp:2:5:2:5 | declaration of f |
 | extern.cpp:2:5:2:5 | f |
 | extern.cpp:2:7:2:7 | (unnamed parameter 0) |
-| extern.cpp:2:7:2:7 | declaration of 1st parameter |
-| extern.cpp:4:1:4:58 | // Currently we don't have an element for this declaration |

cpp/ql/test/library-tests/templates/extern/elements.ql

@@ -1,7 +1,6 @@
 import cpp
 
-from Element e
+from Declaration d
 where
-  e.getLocation().getFile().getBaseName() != "" and
-  not e instanceof Container
-select e
+  d.getLocation().getFile().getBaseName() != ""
+select d