scanner: Don't try to copy c:type if we're parsing (element-type)

scanner: Don't try to copy c:type if we're parsing (element-type)

Commit 81abc2eb63317003a11d1484e84698a37e8ec035 tries harder to keep
the c:type if it was overriden by a (type) annotation.  However, the
_resolve() function was also called for (element-type), which had
undesirable effects - we'd copy the container c:type to the element
type.

Fix this by splitting out the c:type preservation to only happen when
processing toplevel types.

https://bugzilla.gnome.org/show_bug.cgi?id=656931