Correctly identify tempfiles once symlinks are resolved (#3726)

Some linters will expand the paths of symlinked tempfiles when
reporting them back to ALE. This ensures that if they do, the filename
is still flagged appropriately as being temporary.

Author: joshpencheon

autoload/ale/path.vim

@@ -124,11 +124,16 @@ function! ale#path#IsAbsolute(filename) abort
 endfunction
 
 let s:temp_dir = ale#path#Simplify(fnamemodify(ale#util#Tempname(), ':h:h'))
+let s:resolved_temp_dir = resolve(s:temp_dir)
 
 " Given a filename, return 1 if the file represents some temporary file
-" created by Vim.
+" created by Vim. If the temporary location is symlinked (e.g. macOS), some
+" linters may report the resolved version of the path, so both are checked.
 function! ale#path#IsTempName(filename) abort
-    return ale#path#Simplify(a:filename)[:len(s:temp_dir) - 1] is# s:temp_dir
+    let l:filename = ale#path#Simplify(a:filename)
+
+    return l:filename[:len(s:temp_dir) - 1] is# s:temp_dir
+    \|| l:filename[:len(s:resolved_temp_dir) - 1] is# s:resolved_temp_dir
 endfunction
 
 " Given a base directory, which must not have a trailing slash, and a