ensure Dr. Memory and drcov work under Chrome Win8 syscall sandbox

On win7 the sandbox was hooking wrappers, while on win8 they're using the new kernel support:

https://www.chromium.org/developers/design-documents/sandbox#TOC-Process-mitigation-policies-Win32k-lockdown-

```
On Windows 8 and above, a new mitigation policy was added, accessible via
called ProcessSystemCallDisablePolicy which allows selective disabling of
system calls available from the target process. On Windows 10 there is an
additional policy that can be applied called ProcessFontDisablePolicy.
```

Could maybe affect drcov too -- we may want to put Chrome on a Win8 machine and see.