Previously, error strings were kept in arrays for each subdirectory and
err.c would iterate over them all and insert them at init time to a hash
table.

This means that, even if you have a shared library and lots of processes
using that, each process has ~30KB of private memory from building that
hash table.

This this change, all the error strings are built into a sorted list and
are thus static data. This means that processes can share the error
information and it actually saves binary space because of all the
pointer overhead in the old scheme. Also it saves the time taken
building the hash table at startup.

This removes support for externally-supplied error string data.

Change-Id: Ifca04f335c673a048e1a3e76ff2b69c7264635be

find -name CMakeLists.txt -type f | xargs sed -e 's/\t/  /g' -i

Change-Id: I01636b1849c00ba918f48828252492d99b0403ac

Implementations of ENGINEs often don't want to implement every function.
This change adds an error code for those situations.

Change-Id: Id6b7eace36d06ffad7f347f556d942d447d8a2fd
Reviewed-on: https://boringssl-review.googlesource.com/1920
Reviewed-by: Wan-Teh Chang <wtc@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)