Closure error with ASan + minimal_runtime

When using ASan with MINIMAL_RUNTIME=1 and -O2, closure errors out with:

```
building:ERROR: /tmp/emscripten_temp/test_exceptions.wasm.js.jso.js.jso.js:33: ERROR - [JSC_UNDEFINED_VARIABLE] variable runtimeInitialized is undeclared
if (runtimeInitialized) return _asan_c_load_1(ptr);
^^^^^^^^^^^^^^^^^^
```

From what I gather, MINIMAL_RUNTIME does not include the `runtimeInitialized` variable, but that variable is used by `_asan_js_load_1` and friends in runtime_safe_heap.js. What is the most appropriate course of action?

1) disallow using ASan with MINIMAL_RUNTIME
2) Add versions of `_asan_js_load1` and friends for use with MINIMAL_RUNTIME that do not depend on `runtimeInitialized` and assume it to be true.
3) something else?