CMake Buildsystem: Enable visibility settings for binaries

This should not matter, but makes the add_qtc_executable targets
match up with the PCH, so that they should build a bit faster.

Change-Id: Ibecaaf7fd98d5b927d52e4956b1bea4a5775afba
Reviewed-by: Cristian Adam <cristian.adam@qt.io>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

cmake/QtCreatorAPI.cmake

@@ -838,6 +838,8 @@ function(add_qtc_executable name)
     INSTALL_RPATH "${_RPATH_BASE}/${_RELATIVE_LIB_PATH}"
     RUNTIME_OUTPUT_DIRECTORY "${_output_binary_dir}/${_DESTINATION}"
     QT_SKIP_TRANSLATION "${skip_translation}"
+    CXX_VISIBILITY_PRESET hidden
+    VISIBILITY_INLINES_HIDDEN ON
     ${_arg_PROPERTIES}
   )
   append_extra_translations("${name}" "${_arg_EXTRA_TRANSLATIONS}")