Merge pull request #7032 from tSchubes/patch-1

grunt.util.ISpawnOptions.cmd is optional

gruntjs/gruntjs.d.ts

@@ -1172,7 +1172,7 @@ declare module grunt {
             /**
              * The command to execute. It should be in the system path.
              */
-            cmd: string
+            cmd?: string
 
             /**
              * If specified, the same grunt bin that is currently running will be