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)

src/if_perl.xs

@@ -1558,7 +1558,7 @@ Buffers(...)

		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;
	    }

src/version.c

@@ -766,6 +766,8 @@ static char *(features[]) =

static int included_patches[] =
{   /* Add new patch number below this line */
/**/
    1576,
/**/
    1575,
/**/