patch 8.0.1576: Perl VIM::Buffers() does not find every buffer

Problem:    Perl VIM::Buffers() does not find every buffer.
Solution:   Also find unlisted buffer by number or name. (Chris Weyl,
            closes #2692)
diff --git a/src/if_perl.xs b/src/if_perl.xs
index 2e6004b..7b45033 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -1558,7 +1558,7 @@
 
 		pat = (char_u *)SvPV(sv, len);
 		++emsg_off;
-		b = buflist_findpat(pat, pat+len, FALSE, FALSE, FALSE);
+		b = buflist_findpat(pat, pat + len, TRUE, FALSE, FALSE);
 		--emsg_off;
 	    }