win32.c: fix offset

* win32/win32.c (opendir_internal): fix offset not to overwrite a
  backslash.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51677 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

win32/win32.c

@@ -1951,7 +1951,7 @@ opendir_internal(WCHAR *wpath, const char *filename)
 	    WCHAR *tmppath = malloc((pathlen + len + 1) * sizeof(WCHAR));
 	    memcpy(tmppath, wpath, pathlen * sizeof(WCHAR));
 	    tmppath[pathlen] = L'\\';
-	    memcpy(tmppath + pathlen, fd.cFileName, len * sizeof(WCHAR));
+	    memcpy(tmppath + pathlen + 1, fd.cFileName, len * sizeof(WCHAR));
 	    if (rb_w32_reparse_symlink_p(tmppath))
 		SetBit(p->bits, BitOfIsRep(p->nfiles));
 	    free(tmppath);