Fix verilog prep (bp #1932) (#2079)

* fix a test not detecting verilog name conflicts.

(cherry picked from commit 48e56c9f)

* bug fix for VerilogPrep using wrong type.

(cherry picked from commit b2726dff)

* fix for LoweringCompilersSpec.

(cherry picked from commit 61f3e886

)

Co-authored-by: Jiuyang liu <liujiuyang1994@gmail.com>