widen the range of max_bytes_used for T1969, to reduce spurious

failures

testsuite/tests/perf/compiler/all.T

@@ -26,7 +26,7 @@ test('T1969',
                              #                 5717704 (x86/Windows 17/05/10)
                              #                 6149572 (x86/Linux, 31/12/09)
       if_wordsize(64,
-          compiler_stats_range_field('max_bytes_used', 9000000, 15)),
+          compiler_stats_range_field('max_bytes_used', 9000000, 20)),
                                   # looks like the peak is around 10M, but we're
                                   # unlikely to GC exactly on the peak.
                                   # varies quite a lot with CLEANUP and BINDIST,