[asan] Intercept SetUnhandledExceptionFilter.

In this diff I update the code for asan on Windows, so we can intercept
SetUnhandledExceptionFilter and catch some exceptions depending on the result of
IsHandledDeadlyException() (which depends on asan flags).

This way we have the same behavior on Windows and Posix systems.
On Posix, we intercept signal and sigaction, so user's code can only register
signal handlers for signals that are not handled by asan.
After this diff, the same happens on Windows, user's code can only register
exception handlers for exceptions that are not handled by asan.

Differential Revision: https://reviews.llvm.org/D29463

llvm-svn: 293957