Make sure to install QtStandaloneTestsConfig.cmake.in

Otherwise leaf modules fail to configure.
Amends de3a806def

Change-Id: Ie304c0021ada9911044abdb7e460b8da8e986a8f
Reviewed-by: Leander Beernaert <leander.beernaert@qt.io>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

cmake/QtBaseGlobalTargets.cmake

@@ -187,6 +187,7 @@ qt_copy_or_install(FILES
                    cmake/QtModuleDependencies.cmake.in
                    cmake/QtModuleToolsDependencies.cmake.in
                    cmake/QtModuleToolsConfig.cmake.in
+                   cmake/QtStandaloneTestsConfig.cmake.in
                    cmake/QtPlugins.cmake.in
                    cmake/QtPluginConfig.cmake.in
                    cmake/QtPluginDependencies.cmake.in