extmod/mod: Added Python linkage for SO_BROADCAST for UDP broadcast

[xuancong84]

This PR solves the issue (#8729 ) for SO_BROADCAST to work.

[github-actions]

Code size report:

   bare-arm:    +0 +0.000% 
minimal x86:    +0 +0.000% 
   unix x64:    +0 +0.000% standard
      stm32:   +28 +0.007% PYBV10
     mimxrt:   +16 +0.004% TEENSY40
        rp2:    +0 +0.000% PICO
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS