It seems OS X actually cares about symbol resolution and dependencies
when you create a dylib. Probably because they do two-level name
resolution.

(Obligatory disclaimer: BoringSSL does not have a stable ABI and is thus
not suitable for a traditional system-wide library.)

BUG=539603

Change-Id: Ic26c4ad23840fe6c1f4825c44671e74dd2e33870
Reviewed-on: https://boringssl-review.googlesource.com/6131
Reviewed-by: Adam Langley <alangley@gmail.com>