Fix #1716 - Replace tempdir() with a wrapper to preserve TMPDIR

ale_linters/verilog/verilator.vim

@@ -7,7 +7,7 @@ if !exists('g:ale_verilog_verilator_options')
 endif
 
 function! ale_linters#verilog#verilator#GetCommand(buffer) abort
-    let l:filename = tempname() . '_verilator_linted.v'
+    let l:filename = ale#util#Tempname() . '_verilator_linted.v'
 
     " Create a special filename, so we can detect it in the handler.
     call ale#engine#ManageFile(a:buffer, l:filename)