EC_ILOG cleanups.

Mark _BitScanReverse as an intrinsic, as this is not done by default
 in _DEBUG mode (thanks to Bjoern D. Rasmussen for the suggestion).
Move the declaration of ec_ilog() to where the macro using it is
 defined, to ensure it is available when the macro is used.
Thanks to John Ridges for the report.
2 files changed