Fix perl syntax error in fcopy

Fix:

| Global symbol "$preinst" requires explicit package name at bin/fcopy line 324.

Introduced in:

| commit 981277f473ac938a24e7c4c59df0f1a45f728d4b
| Author: Thomas Lange <lange@informatik.uni-koeln.de>
| Date:   Sat Aug 10 18:33:15 2013 +0200
|
|     do not set atime/mtime if preinst was used, Closes: #699535