...when a class derives from multiple (non-virtual) instances of one base class,
and the override disambiguates which of those instances' member to call.

That was the case with SwXTextDocument::queryAdapter
(sw/source/uibase/uno/unotxdoc.cxx), where SwXTextDocument derives from
cppu::OWeakObject through both SwXTextDocumentBaseClass and SfxBaseModel, but
calling queryAdapter through a pointer to SwXTextDocumentBaseClass apparently
needs to call OWeakObject::queryAdapter on the second, SfxBaseModel-inherited
OWeakObject base instance, or else CppunitTest_sw_macros_test fails.

Who knows what other instances of similar non-unnecessary overrides have been
removed with the help of broken loplugin:unnecessaryoverride, for which there
were no tests that started to fail...

Turns out .clang-format lacked "ReflowComments: false" to not break the special
"// expected-error {{...}}" etc. comments in compilerplugins/clang/test/.

Also, use a better location to report loplugin:unnecessaryoverride, to keep
clang-format and loplugin:unnecessaryoverride from fighting over how to split
lines and where to put the comment in
compilerplugins/clang/test/unnecessaryoverride.cxx.

Change-Id: I3b24df24369db12f8ec1080d6c9f7b70ff561a16
Reviewed-on: https://gerrit.libreoffice.org/44418Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>