Remove SSL_OP_EPHEMERAL_RSA quirk.

Also fix a place where fixes for the condition for sending ServerKeyExchange in
s3_srvr.c were never propogated to d1_srvr.c. Tidy up that logic to use
ssl_cipher_requires_server_key_exchange and simplify the PSK check.

Change-Id: Ie36d378f733e59a8df405bc869f2346af59bd574
Reviewed-on: https://boringssl-review.googlesource.com/1283
Reviewed-by: Adam Langley <agl@google.com>