[locale] Add a CMake option for debugging

src/modules/locale/CMakeLists.txt

@@ -1,8 +1,10 @@
 # When debugging the timezone widget, add this debugging definition
 # to have a debugging-friendly timezone widget, debug logging,
 # and no intrusive timezone-setting while clicking around.
-#
-# add_definitions( -DDEBUG_TIMEZONES )
+option( DEBUG_TIMEZONES "Debug-friendly timezone widget." OFF )
+if( DEBUG_TIMEZONES )
+    add_definitions( -DDEBUG_TIMEZONES )
+endif()
 
 include_directories( ${PROJECT_BINARY_DIR}/src/libcalamaresui )