windows: fix build on pre-Win10 systems
windows: fix build on pre-Win10 systems

The use of DBG_PRINTEXCEPTION_WIDE_C was added for Win10 support,
but that define doesn't exist in older versions which means we fail
to build.  Put it behind an ifdef check to work everywhere.

Change-Id: Ibab8bddd5c19b4b50e356f59edeb3873c3104569
Reviewed-on: https://chromium-review.googlesource.com/441525
Reviewed-by: Mark Mentovai <f1b5a91d4d6ad523f2610114591c007e75d15084@chromium.org>

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