Suppress over-eager compiler warning in tests

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/tests/suites/test_suite_alignment.function b/tests/suites/test_suite_alignment.function
index 31d877c..39bccb0 100644
--- a/tests/suites/test_suite_alignment.function
+++ b/tests/suites/test_suite_alignment.function
@@ -2,6 +2,8 @@
 #include "../library/alignment.h"
 
 #include <stdint.h>
+
+#pragma clang diagnostic ignored "-Wunreachable-code"
 /* END_HEADER */
 
 /* BEGIN_CASE */