Add checks to the return value of EVP_Cipher to prevent silent encryption failure.

PR#1767

Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit fe78f08d1541211566a5656395186bfbdc61b6f8)
Delete unused file

Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit 4b87706d20f0a2fdf2e8f1b90256e141c487ef47)

Conflicts:
	ssl/d1_enc.c
Check EVP_Cipher return values for SSL2

Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit 81ec01b21767da5e5f0c03ad79b4d3dc9b632393)
Remove more references to dtls1_enc

Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit eceef8fb865eb5de329b27ea472d4fdea4c290fe)
Fix warning in ssl2_enc

Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit f9ea4deba006ee45a61e5f406f12c936b9bc162e)