Only run memory poisoning metatests when poisoning

When we cannot memory poison due to platform constraints, do not attempt
to run memory poisoning metatests (but still run other ASan metatests).

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/programs/test/metatest.c b/programs/test/metatest.c
index 1724aed..6fcf52a 100644
--- a/programs/test/metatest.c
+++ b/programs/test/metatest.c
@@ -366,6 +366,7 @@
     { "double_free", "asan", double_free },
     { "read_uninitialized_stack", "msan", read_uninitialized_stack },
     { "memory_leak", "asan", memory_leak },
+#if defined(MBEDTLS_TEST_MEMORY_CAN_POISON)
     { "test_memory_poison_0_0_8_r", "asan", test_memory_poison },
     { "test_memory_poison_0_0_8_w", "asan", test_memory_poison },
     { "test_memory_poison_0_7_8_r", "asan", test_memory_poison },
@@ -382,6 +383,7 @@
     { "test_memory_poison_7_0_1_w", "asan", test_memory_poison },
     { "test_memory_poison_7_1_2_r", "asan", test_memory_poison },
     { "test_memory_poison_7_1_2_w", "asan", test_memory_poison },
+#endif /* MBEDTLS_TEST_MEMORY_CAN_POISON */
     { "mutex_lock_not_initialized", "pthread", mutex_lock_not_initialized },
     { "mutex_unlock_not_initialized", "pthread", mutex_unlock_not_initialized },
     { "mutex_free_not_initialized", "pthread", mutex_free_not_initialized },