Security: disable the elixir checker by default.

This executes the code your files. This is probably fine if you wrote
the files yourself, but it can be a problem if you're trying to check
third party files. If you are 100% willing to let Vim run the code in
your files, set g:syntastic_enable_elixir_checker to 1 in your vimrc.

References:

https://groups.google.com/d/msg/elixir-lang-talk/B29noPHvQ-8/9JvSGPop7n0J

plugin/syntastic.vim

@@ -19,7 +19,7 @@ if has('reltime')
     lockvar! g:syntastic_start
 endif
 
-let g:syntastic_version = '3.4.0-106'
+let g:syntastic_version = '3.4.0-107'
 lockvar g:syntastic_version
 
 " Sanity checks {{{1

plugin/syntastic/loclist.vim

@@ -49,6 +49,7 @@ endfunction " }}}2
 function! g:SyntasticLoclist.isNewerThan(stamp) " {{{2
     if !exists("self._stamp")
         let self._stamp = []
+        return 0
     endif
     return syntastic#util#compareLexi(self._stamp, a:stamp) > 0
 endfunction " }}}2

plugin/syntastic/registry.vim

@@ -30,7 +30,7 @@ let s:defaultCheckers = {
         \ 'dart':        ['dartanalyzer'],
         \ 'docbk':       ['xmllint'],
         \ 'dustjs':      ['swiffer'],
-        \ 'elixir':      ['elixir'],
+        \ 'elixir':      [],
         \ 'erlang':      ['escript'],
         \ 'eruby':       ['ruby'],
         \ 'fortran':     ['gfortran'],

syntax_checkers/elixir/elixir.vim

@@ -24,6 +24,11 @@ function! SyntaxCheckers_elixir_elixir_IsAvailable() dict
 endfunction
 
 function! SyntaxCheckers_elixir_elixir_GetLocList() dict
+    if !exists('g:syntastic_enable_elixir_checker') || !g:syntastic_enable_elixir_checker
+        call syntastic#log#error('checker elixir/elixir: checks disabled for security reasons; ' .
+            \ 'set g:syntastic_enable_elixir_checker to 1 to override')
+        return []
+    endif
 
     let make_options = {}
     let compile_command = 'elixir'