Correct path to original author info.

Index: libpam-mount-2.13/doc/pmvarrun.8
===================================================================
--- libpam-mount-2.13.orig/doc/pmvarrun.8	2011-12-15 13:12:10.000000000 +0100
+++ libpam-mount-2.13/doc/pmvarrun.8	2011-12-19 07:15:04.507065749 +0100
@@ -55,5 +55,5 @@ This manpage was originally written by B
 <calvin@debian.org> for the Debian distribution of libpam\-mount but
 may be used by others.
 .PP
-See /usr/share/doc/packages/pam_mount/AUTHORS for the list of original authors
+See /usr/share/doc/packages/libpam\-mount/copyright for the list of original authors
 of pam_mount.
