Fix showmap SIGSEGV.

Bug: http://b/26084907
Change-Id: I6ed8a26b93d90348d2bb806ccd7752a1a76144a6
diff --git a/showmap/showmap.c b/showmap/showmap.c
index 8cf9413..2d60216 100644
--- a/showmap/showmap.c
+++ b/showmap/showmap.c
@@ -312,7 +312,7 @@
     printf("%8d %8d %8d %8d %8d %8d %8d %8d", size,
             rss, pss,
             shared_clean, shared_dirty,
-            private_clean, private_dirty, mi->swap);
+            private_clean, private_dirty, swap);
     if (!verbose && !addresses) {
         printf("%4d ", count);
     }