patch 9.0.1478: filetypes for *.v files not detected properly

Problem:    Filetypes for *.v files not detected properly.
Solution:   Use the file contents to detect the filetype. (Turiiya,
            closes #12281)

runtime/filetype.vim

@@ -2303,8 +2303,8 @@ au BufNewFile,BufRead *.vr,*.vri,*.vrh		setf vera
 " Vagrant (uses Ruby syntax)
 au BufNewFile,BufRead Vagrantfile		setf ruby
 
-" Verilog HDL
-au BufNewFile,BufRead *.v			setf verilog
+" Verilog HDL, V or Coq
+au BufNewFile,BufRead *.v			call dist#ft#FTv()
 
 " Verilog-AMS HDL
 au BufNewFile,BufRead *.va,*.vams		setf verilogams