[sanitizer] Add weak hooks for Windows.

Add support for weak hooks on Windows, as we do on Linux and Darwin.
As we use the macro: `SANITIZER_INTERFACE_WEAK_DEF()` it was not necessary to
modify the header file: `sanitizer_common_interceptors.h`.

After this diff, many tests were fixed for libFuzzer.

Differential Revision: https://reviews.llvm.org/D29562

llvm-svn: 294409