Nullability check for mman module.

Bugs: b/245972273
Test: adb shell
Change-Id: Ib5c4887d89581eaedcf4a3e128811a6a374a8d1b
diff --git a/tests/sys_mman_test.cpp b/tests/sys_mman_test.cpp
index e403ea5..803852a 100644
--- a/tests/sys_mman_test.cpp
+++ b/tests/sys_mman_test.cpp
@@ -218,7 +218,10 @@
 }
 
 TEST(sys_mman, mremap) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnonnull"
   ASSERT_EQ(MAP_FAILED, mremap(nullptr, 0, 0, 0));
+#pragma clang diagnostic pop
 }
 
 constexpr size_t kHuge = size_t(PTRDIFF_MAX) + 1;