Stop pyexpect from closing serial port when running with WSL2
Remove makefile flags & opts making it too silent. At some point it makes a lot of useful info just disappear. There are external means of silencing make, so probably best to leave useful data always available
Replace SPIFFS with LittleFS in FS test
Re-use certs-from-mozilla.py in FS test
Fix libc tests w/o -fno-builtin not actually testing anything, also add the flag via .globals.h in case it breaks
Fix libc tests generating warnings when using invalid (but safe) size arguments
