headersclean enforces various rules which all Qt headers are supposed to
abide by. It fails compilation if these rules are broken.
These rules should be followed also by modules hosted outside of
qtbase. Split the test up so that it can be easily reused by other
modules.
Change-Id: Icf09cbfde411c926ed87914dc821e6dfc569b0de
Reviewed-by: Jason McDonald <jason.mcdonald@nokia.com>
