Improved stats for Trac #1969

With my latest commits

  76a5477b Move zonking out of tcFamTyPats
  b255ae7b Orient improvement constraints better

perf has improved slightly for T1969:

allocs:    733M -> 26M
residency: 43M  -> 41M

I don't know exactly why, but hey, it's good

testsuite/tests/perf/compiler/all.T

@@ -28,7 +28,7 @@ setTestOpts(no_lint)
 #    really changed, then you know there's an issue.
 
 test('T1969',
-     [expect_broken(12437),
+     [# expect_broken(12437),
       compiler_stats_num_field('peak_megabytes_allocated', # Note [residency]
           [(wordsize(32), 30, 15),
              # 2010-05-17 14 (x86/Windows)