Remove all the logic managing key types that aren't being used anymore.

Change-Id: I101369164588048e64ba1c84a6b8aac8f3a221cd
Reviewed-on: https://boringssl-review.googlesource.com/1567
Reviewed-by: Adam Langley <agl@google.com>

Avoid needing to manually increment the reference count and using the right
lock, both here and in Chromium.

Change-Id: If116ebc224cfb1c4711f7e2c06f1fd2c97af21dd
Reviewed-on: https://boringssl-review.googlesource.com/1415
Reviewed-by: Adam Langley <agl@google.com>

Reference counting should be internal to the type, otherwise callers need to
know which lock to use.

Change-Id: If4d805876a321ef6dece115c805e605584ff311e
Reviewed-on: https://boringssl-review.googlesource.com/1414
Reviewed-by: Adam Langley <agl@google.com>

Custom RSA and ECDSA keys may not expose the key material. Plumb and "opaque"
bit out of the *_METHOD up to EVP_PKEY. Query that in ssl_rsa.c to skip the
sanity checks for certificate and key matching.

Change-Id: I362a2d5116bfd1803560dfca1d69a91153e895fc
Reviewed-on: https://boringssl-review.googlesource.com/1255
Reviewed-by: Adam Langley <agl@google.com>

Building without RSA support is unreasonable. Changes were made by
running

find . -type f -name *.c | xargs unifdef -m -U OPENSSL_NO_RSA
find . -type f -name *.h | xargs unifdef -m -U OPENSSL_NO_RSA

using unifdef 2.10 and some newlines were removed manually.

Change-Id: Iea559e2d4b3d1053f28a4a9cc2f7a3d1f6cabd61
Reviewed-on: https://boringssl-review.googlesource.com/1095
Reviewed-by: Adam Langley <agl@google.com>

Found no users of the functions which control the feature. (Also I don't
particularly want to port all of that to CBS...)

Change-Id: I55da42c44d57252bd47bdcb30431be5e6e90dc56
Reviewed-on: https://boringssl-review.googlesource.com/1061
Reviewed-by: Adam Langley <agl@google.com>

If we need an extension, we can implement it in-library.

Change-Id: I0eac5affcd8e7252b998b6c86ed2068234134b08
Reviewed-on: https://boringssl-review.googlesource.com/1051
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.)