[ImportVerilog] Fix unknown name caused by local variables.

[hailongSun2000]

If we don't collect the local temporary variables, it triggers the following error:
For example:

module Temporary();
  int x, y, z;
  always_comb begin
    automatic int a;
    a = x + 1;
    y = a;
    a = a + 1;
    z = a;
  end
endmodule

Temporary.sv:5:5: error: unknown name `a`
    a = x + 1;

[uenoku]

LGTM! Could you add a test?

[hailongSun2000]

LGTM! Could you add a test?

No problem! But I'll wait to add it tomorrow. And the IR is the same as non-local variables.

[fabianschuiki]

Thanks for the fix! I agree with @uenoku: once there's a test this is good to go 😃

[hailongSun2000]

Thanks for the fix! I agree with @uenoku: once there's a test this is good to go 😃

I have added the test cases.

[hailongSun2000]

LGTM! Could you add a test?

I have added the test cases.