Move qpointer.cpp → qpointer.qdoc

It contains no implementation. Proof: it includes no headers.

Pick-to: 6.5
Change-Id: I64b42ce799eec05a0faff2021e2b60460695e192
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
(cherry picked from commit 3321101d8f199f998c9f2b27d997000c38a30454)
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/CMakeLists.txt

@@ -175,7 +175,7 @@ qt_internal_add_module(Core
         kernel/qobjectcleanuphandler.cpp kernel/qobjectcleanuphandler.h
         kernel/qobjectdefs.h
         kernel/qobjectdefs_impl.h
-        kernel/qpointer.cpp kernel/qpointer.h
+        kernel/qpointer.h
         kernel/qproperty.cpp kernel/qproperty.h kernel/qproperty_p.h
         kernel/qpropertyprivate.h
         kernel/qsequentialiterable.cpp kernel/qsequentialiterable.h