[Windows MSVC CFG] Add support for CFG, and enable on chrome.exe & chrome_elf.dll.
CFG supported on x86 and x64 >= Windows 8.1 Update (KB3000850).
Initial support for Control Flow Guard. "Enable" on chrome.exe to take
advantage of MS system32 dll CFG. Also compile and link chrome_elf with CFG.
NOTE: As ASLR is disabled in debug builds, so too is CFG.
Using the dumpbin tool from the Visual Studio command prompt, run "dumpbin /headers /loadconfig" against chrome.exe or chrome_elf.dll. 1) "DLL characteristics" now includes "Control Flow Guard", and 2) if code was compiled with cfg there will be "load config" for "Guard CF" function table and flags.