[Snek] [keith-packard/snek] e69392: Build in -std=c18 mode

[Keith Packard]

  Branch: refs/heads/empty-input
  Home:   https://github.com/keith-packard/snek
  Commit: e69392615805fbede5022f051ebfe80565c5587d
      https://github.com/keith-packard/snek/commit/e69392615805fbede5022f051ebfe80565c5587d
  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/samd21/ao-arch-funcs.h
    M chips/samd21/ao-arch.h
    M snek-pow.c
    M snek.defs

  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: 5145e0e3ac28f029e4ac34e0cd1c0870877a1199
      https://github.com/keith-packard/snek/commit/5145e0e3ac28f029e4ac34e0cd1c0870877a1199
  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/e69392615805%5E...5145e0e3ac28