Don't include .extern and .hidden on OS X.

Change-Id: I582eaa2ff922bbf1baf298a5c6857543524a8d4e
Reviewed-on: https://boringssl-review.googlesource.com/3810
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>
1 file changed