bug 2006: do not crash when paying a lost item fine

Qualified call to MarkIssueReturned with 'C4::Circulation'.
It looks like there is still a subtle bug with exporting
subs between modules that use each other.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>

C4/Accounts.pm

@@ -268,7 +268,7 @@ EOT
 
 sub returnlost {
     my ( $borrowernumber, $itemnum ) = @_;
-    MarkIssueReturned( $borrowernumber, $itemnum );
+    C4::Circulation::MarkIssueReturned( $borrowernumber, $itemnum );
     my $borrower = C4::Members::GetMember( $borrowernumber, 'borrowernumber' );
     my @datearr = localtime(time);
     my $date = ( 1900 + $datearr[5] ) . "-" . ( $datearr[4] + 1 ) . "-" . $datearr[3];