R600/SI: Fix missing -verify-machineinstrs on a test
R600/SI: Fix broken check lines and modernize prefixes

Use -LABEL and remove -CHECK
R600/SI: Add additional tests for i1 loads
R600: Fix assert on copy of an i1 on pre-SI

i1 is not a legal type on Evergreen, so this combine proceeded
and tried to produce a bitcast between i1 and i8.