Install plugin related .cmake.in files

This fixes the build when building qtsvg, qtimageformats, etc.

Amends 0900298d46

Change-Id: Ie732ef6faa99e2ebe7e8da6ee2aa5fc0cf59d3f3
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

cmake/QtBaseGlobalTargets.cmake

@@ -117,6 +117,8 @@ qt_copy_or_install(FILES
                    cmake/QtModuleDependencies.cmake.in
                    cmake/QtModuleToolsDependencies.cmake.in
                    cmake/QtModuleToolsConfig.cmake.in
+                   cmake/QtPluginConfig.cmake.in
+                   cmake/QtPluginDependencies.cmake.in
     DESTINATION "${__GlobalConfig_install_dir}"
 )