Test the width of expression for shift amounts.
Test the width of expression for shift amounts.

The right-operand of shift expressions is self-determined, but we still
need to run a test_width to get the PExpr decorated with types and
expression widths.
themperek/iverilog,themperek/iverilog,CastMi/iverilog,CastMi/iverilog,CastMi/iverilog,themperek/iverilog