Add syntax check verilog and systemverilog

[Kocha]

I used verilog and systemverilog.
I am glad if you add.

[lcd047]

I added the verilog checker to the gcc_refactor branch, with a number of changes. Among other things this allows verilator options to be specified in a config file, and handles include directories and compiler flags; see the wiki for more details. Commit 5c75519.

There doesn't seem to be any need for a separate checker for SystemVerilog. Vim has no separate filetype systemverilog, and the extended syntax is enabled by default in verilator.

[Kocha]

I have tried.
Thank you.