patch 9.0.0935: when using dash it may not be recognize as filetype "sh"

Problem:    When using dash it may not be recognize as filetype "sh".
Solution:   Add checks for "dash". (Eisuke Kawashima,closes #11600)

src/testdir/test_filetype.vim

@@ -704,6 +704,13 @@ let s:script_checks = {
       \		['__libc_start_main and something']],
       \ 'clojure': [['#!/path/clojure']],
       \ 'scala': [['#!/path/scala']],
+      \ 'sh':  [['#!/path/sh'],
+      \         ['#!/path/bash'],
+      \         ['#!/path/bash2'],
+      \         ['#!/path/dash'],
+      \         ['#!/path/ksh'],
+      \         ['#!/path/ksh93']],
+      \ 'csh': [['#!/path/csh']],
       \ 'tcsh': [['#!/path/tcsh']],
       \ 'zsh': [['#!/path/zsh']],
       \ 'tcl': [['#!/path/tclsh'],

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    935,
 /**/
     934,
 /**/