Put the right number of Ls after 64-bit constants.

Change-Id: I9f96259f21e42a84b9ebe20655fe0edb31f41892
diff --git a/tests/math_test.cpp b/tests/math_test.cpp
index 8e0abdb..458a146 100644
--- a/tests/math_test.cpp
+++ b/tests/math_test.cpp
@@ -37,7 +37,7 @@
     double d;
     uint64_t i;
   } u;
-  u.i = 0x000fffffffffffffL;
+  u.i = 0x000fffffffffffffLL;
   return u.d;
 }