testsuite: Disable derefnull when built with LLVM
Like division-by-zero (see #10332 (closed)), LLVM does not guarantee any semantics when dereferencing null-pointers. Consequently this test actually passes when built with LLVM.
Like division-by-zero (see #10332 (closed)), LLVM does not guarantee any semantics when dereferencing null-pointers. Consequently this test actually passes when built with LLVM.