Fix compiler options

Fix compiler options

Adds '/ZH:SHA_256' '/CETCOMPAT' '/sdl' to compiler and '/SafeSEH' to x86 linker
command lines
These changes were prompted by binskim https://github.com/microsoft/binskim

Note: Rule BA2004 (Warning_NativeWithInsecureStaticLibraryCompilands) is still
      reported for xenvbd_coinst.dll and xencrsh.sys
      Rule BA2018 (Error, empty SEH table) is still reported for xencrsh.sys

Signed-off-by: Owen Smith <owen.smith@citrix.com>