[Snek] [keith-packard/snek] 2da490: test: Add operator precedence tests

[Keith Packard]

  Branch: refs/heads/main
  Home:   https://github.com/keith-packard/snek
  Commit: 2da490be45e017d1c34c2c5c449f1d597aed05da
      https://github.com/keith-packard/snek/commit/2da490be45e017d1c34c2c5c449f1d597aed05da
  Author: Keith Packard <keithp at keithp.com>
  Date:   2021-03-29 (Mon, 29 Mar 2021)

  Changed paths:
    M test/Makefile
    A test/pass-precedence.py

  Log Message:
  -----------
  test: Add operator precedence tests

Snek has inverted the precedence of bitwise and and xor operators;
this test checks those and other less common operators to make sure
they are ordered correctly.

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