Assert that FLT_EVAL_METHOD is 0 for our supported architectures.

Change-Id: I5e847f098c1d80dcb93dddc1b25191b0dc84ebee
diff --git a/tests/float_test.cpp b/tests/float_test.cpp
index 3ef4593..a2b7ecb 100644
--- a/tests/float_test.cpp
+++ b/tests/float_test.cpp
@@ -122,3 +122,7 @@
 #error LDBL_HAS_SUBNORM
 #endif
 }
+
+TEST(float_h, FLT_EVAL_METHOD_exact) {
+  ASSERT_EQ(0, FLT_EVAL_METHOD);
+}