C4701 is "potentially uninitialized local variable 'buf' used". It
sometimes results in false positives, which can now be suppressed
using the macro OPENSSL_SUPPRESS_POTENTIALLY_UNINITIALIZED_WARNINGS.

Change-Id: I15068b5a48e1c704702e7752982b9ead855e7633
Reviewed-on: https://boringssl-review.googlesource.com/3160
Reviewed-by: Adam Langley <agl@google.com>

Now that much of EVP has been normalized to 0/1, a lot of code can just use
boolean operators. (As can some code which was already using them...)

Change-Id: I6bb17edfd6f67050bf1706d59d8f37df57535faa
Reviewed-on: https://boringssl-review.googlesource.com/3875
Reviewed-by: Adam Langley <agl@google.com>

All EVP_PKEY types return 1 on that. (It can go away entirely when
EVP_PKEY_HMAC is gone.) This removes a place internally where we're sensitive
to the failure code.

Change-Id: Ic6cda2da9337ba7ef1c66a18e40c5dcc44fcf840
Reviewed-on: https://boringssl-review.googlesource.com/3871
Reviewed-by: Adam Langley <agl@google.com>

It was already almost there. Just a malloc failure away. now all the
EVP_Digest{Sign,Verify}* functions may be used without worrying about -1 return
values.

Change-Id: I96a9750b300010615979bd5f1522b1d241764665
Reviewed-on: https://boringssl-review.googlesource.com/2064
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.)