I’ve submitted a pull request (#455 commit 33197cea1f567fcdaab2fe98a7644603b1165177) that implements the per-file compiler flag feature for all exporters.
A new combo box is added for all files listed in the file browser that are selected for compilation. In the combo box, you can create or select a compiler flag setting. Note that in the file browser you only set the setting name. The actual compiler flags are set in the exporter properties.
Once you have created a setting, the property sheet for the exporter will list it directly under “Extra Compiler Flags” with the title “Extra Compiler Flags for YourSetting”. You can list the flags for the exporter there and they will be included for just those files that have the corresponding setting selected.
I’d be happy to receive feedback or suggestions for further improvements and enhancements.