Build breaks for ESP32 if config flavour is MinSizeRel

[josesimoes]

This was spotted after changing AppVeyor build configuration of develop branch to MinSizeRel.
The build matrix for ESP32 broke the build.

See the log here

Had to manually set the build configuration for ESP32 to Debug.

Tasks:

• Fix whatever is required in the ESP32 so we can have a build with MinSizeRel
• Revert changes in the override configuration for ESP32 in appveyor.yml (see Change build configuration of develop branch to MinSizeRel nf-interpreter#777)

[AdrianSoundy]

Issue can be closed

[josesimoes]

Seems that this is not working as expected. Reopening.