rtl/amiga: in legacy MatchFirst, revert back to the original directory if we used CurrentDir(0), otherwise MatchFirst() will change the directory to SYS: (0 lock is a shortcut to the boot volume)

rtl/amiga/m68k/legacydos.inc

@@ -271,7 +271,11 @@ begin
 
   // if no path is given use the current working dir, or try to lock the dir
   if Path = '' then
-    DirLock := CurrentDir(0)
+  begin
+    DirLock := CurrentDir(0);
+    if DirLock <> 0 then
+      CurrentDir(DirLock);
+  end
   else
     DirLock := Lock(PChar(Path), ACCESS_READ);
   //