compare has a syntax error where it is missing the path to sem().
BUG=skia:

Review URL: https://codereview.chromium.org/1420963010
diff --git a/bin/compare b/bin/compare
index 95d4100..794cb72 100755
--- a/bin/compare
+++ b/bin/compare
@@ -45,7 +45,7 @@
     am, bm = m(a[key]), m(b[key])
     if have_scipy:
         _, p = scipy.stats.mannwhitneyu(a[key], b[key])
-        asem, bsem = scipy.stats.sem(a[key]), sem(b[key])
+        asem, bsem = scipy.stats.sem(a[key]), scipy.stats.sem(b[key])
     ps.append((bm/am, p, key, am, bm, asem, bsem))
 ps.sort(reverse=True)