[Snek] [keith-packard/snek] 35b666: Build in -std=c18 mode

[Keith Packard]

  Branch: refs/heads/empty-input
  Home:   https://github.com/keith-packard/snek
  Commit: 35b666138c8d75d6f454317a505bdb9b624e7e35
      https://github.com/keith-packard/snek/commit/35b666138c8d75d6f454317a505bdb9b624e7e35
  Author: Keith Packard <keithp at keithp.com>
  Date:   2022-12-10 (Sat, 10 Dec 2022)

  Changed paths:
    M chips/avr/ao-arch.h
    M chips/avr/snek-avr.defs
    M chips/qemu/snek-qemu.defs
    M chips/samd21/ao-arch-funcs.h
    M chips/samd21/ao-arch.h
    M chips/samd21/snek-samd21.defs
    M ports/hifive1revb/Makefile
    M snek-pow.c

  Log Message:
  -----------
  Build in -std=c18 mode

Make sure snek code uses only standard C18 language constructs.

Signed-off-by: Keith Packard <keithp at keithp.com>


  Commit: 13ccbd342241fecdc9a904ddaa04fc12f7a8648f
      https://github.com/keith-packard/snek/commit/13ccbd342241fecdc9a904ddaa04fc12f7a8648f
  Author: Keith Packard <keithp at keithp.com>
  Date:   2022-12-10 (Sat, 10 Dec 2022)

  Changed paths:
    M snek-input.c

  Log Message:
  -----------
  Return '' when just <nl> is provided to 'input'

That's what Python does. Snek's behavior of returning None didn't match.

Signed-off-by: Keith Packard <keithp at keithp.com>


Compare: https://github.com/keith-packard/snek/compare/5145e0e3ac28...13ccbd342241