mksymbolsmanpage.pl: Fix showing symbol's last used version

Prior to this change the symbol's deprecated version was erroneously
shown as its last used version.

Bug: https://github.com/curl/curl/commit/4e53b94#commitcomment-55239509
Reported-by: i-ky@users.noreply.github.com
diff --git a/docs/libcurl/mksymbolsmanpage.pl b/docs/libcurl/mksymbolsmanpage.pl
index 46ad80c..d19a93c 100755
--- a/docs/libcurl/mksymbolsmanpage.pl
+++ b/docs/libcurl/mksymbolsmanpage.pl
@@ -86,7 +86,7 @@
           print "Deprecated since $dep\n";
         }
         if($rem) {
-          print "Last used in $dep\n";
+          print "Last used in $rem\n";
         }
     }