Don't install filter-util.pl

This file was getting incorrectly installed with perl since commit
2adbc9b6919cad1240a834325b355e9b2d5efd67, that moved it from t/ to ext/.

diff --git a/installperl b/installperl
index 38f51ea..bfa5d48 100755 (executable)
--- a/installperl
+++ b/installperl
@@ -716,7 +716,7 @@ sub installlib {
 
     # ignore patch backups, RCS files, emacs backup & temp files and the
     # .exists files, .PL files, and test files.
-    return if $name =~ m{\.orig$|\.rej$|~$|^#.+#$|,v$|^\.exists|\.PL$|\.plc$|\.t$|^test\.pl$|^dbm_filter_util.pl$|^\.gitignore$} ||
+    return if $name =~ m{\.orig$|\.rej$|~$|^#.+#$|,v$|^\.exists|\.PL$|\.plc$|\.t$|^test\.pl$|^dbm_filter_util\.pl$|^filter-util\.pl$|^\.gitignore$} ||
              $dir  =~ m{/t(?:/|$)};
     # ignore the cpan script in lib/CPAN/bin, the instmodsh and xsubpp
     # scripts in lib/ExtUtils, the prove script in lib/Test/Harness,