Revert "Revert "VS, WINCE: Fix entry point for Unicode builds""

This reverts commit df01a380f0a1586629db9445173650fbac6de31b.
The VS <= 9 generators have logic that Unicode implies wmain.
Use that in VS >= 10 for consistency across VS versions.
Merge topic 'fix-wince-unicode-entry-point' into next

0e75a337 Revert "Revert "VS, WINCE: Fix entry point for Unicode builds""