Correction of mpv autocompletion

completion/mpv.elv

@@ -38,7 +38,7 @@ fn complete {|@argv|
   var c = (count $argv)
   if (== $c 2) {
     put --speed
-    -files $argv[-1]
+    file:complete $argv[-1] $@extensions
   } elif (== $c 3) {
     if (eq $argv[-2] --speed) {
       put 0.8 0.9 1.0 1.1 1.2
@@ -46,7 +46,7 @@ fn complete {|@argv|
       file:complete $argv[-1] $@extensions
     }
   } else {
-    -files $argv[-1]
+    file:complete $argv[-1] $@extensions
   }
 }