Fix some "possible" divide by 0

Bug: 28529431
Change-Id: I61f638926b2ae63c5f883fc2cfdce19b00ce79c8
diff --git a/oatdump/oatdump.cc b/oatdump/oatdump.cc
index aa4635d..7239a47 100644
--- a/oatdump/oatdump.cc
+++ b/oatdump/oatdump.cc
@@ -1978,7 +1978,7 @@
       size_t sum_of_expansion = 0;
       size_t sum_of_expansion_squared = 0;
       size_t n = method_outlier_size.size();
-      if (n == 0) {
+      if (n <= 1) {
         return;
       }
       for (size_t i = 0; i < n; i++) {