The weird function thing is a remnant of OpenSSL and I think something
weird involving Windows and symbols exported from dlls. These aren't
exposed in the public API, so have everything point to the tables
directly.

This is in preparation for making built-in EC_GROUPs static. (The static
EC_GROUPs won't be able to call a function wrapper.)

BUG=20

Change-Id: If33888430f32e51f48936db4046769aa1894e3aa
Reviewed-on: https://boringssl-review.googlesource.com/10346
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>