clang: fix `-Wimplicit-fallthrough` warning

../../../lib/search/normal.c:75:9: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
        default:
        ^
../../../lib/search/normal.c:75:9: note: insert 'break;' to avoid fall-through
        default:
        ^
        break;

Signed-off-by: Yury V. Zaytsev <yury@shurup.com>
Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

lib/search/normal.c

@@ -72,6 +72,7 @@ mc_search__normal_translate_to_regex (GString * str)
         case '|':
             g_string_insert_c (str, loop, '\\');
             loop++;
+            break;
         default:
             break;
         }