win: Allow frame pointer omission (FPO, /Oy)
win: Allow frame pointer omission (FPO, /Oy)

Chrome disables FPO, but it’s the Visual Studio default, and code should
function correctly with it enabled. It was previously disabled due to
bugs in RtlCaptureContext() as used by Crashpad, but that function is
being replaced in https://codereview.chromium.org/1377963002/.

BUG=crashpad:53
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/1379663003 .

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