Merge pull request #2476 from zachjs/const-arg-width

Fix constants bound to single bit arguments (fixes #2383)

diff --cc frontends/ast/simplify.cc
Simple merge

diff --cc tests/various/const_arg_loop.v
index 76cc67abb7861c00b718c656a599a1ff2fb46eef,567bccc2542f1a06c17fc76c847a4a181d20c689..ed15aa13529b570c0845507556d050f0b88bb2a0
--- 1/tests/various/const_arg_loop.v
--- 2/tests/various/const_arg_loop.v
+++ b/tests/various/const_arg_loop.v
@@@ -66,8 -67,8 +75,9 @@@ module top
      assert property (a == 2);
      assert property (A == 3);
      assert property (x1 == 16);
 +    assert property (x1b == 16);
      assert property (x2 == 4);
      assert property (x3 == 16);
+     assert property (x4 == a << 1);
  `endif
  endmodule