This reverts commits:
- 9158637142
- a90aa64302
- c0d8b83b44

It turns out code outside of BoringSSL also mismatches Init and Update/Final
functions. Since this is largely cosmetic, it's probably not worth the cost to
do this.

Change-Id: I14e7b299172939f69ced2114be45ccba1dbbb704
Reviewed-on: https://boringssl-review.googlesource.com/7793
Reviewed-by: Adam Langley <agl@google.com>

This is in preparation for taking md_len out of SHA256_CTX by allowing us to do
something similar to SHA512_CTX. md32_common.h now emits a static "finish"
function which Final composes with the extraction step.

Change-Id: I314fb31e2482af642fd280500cc0e4716aef1ac6
Reviewed-on: https://boringssl-review.googlesource.com/7721
Reviewed-by: Adam Langley <agl@google.com>

This version is taken from OpenSSL 1.0.2 with tweaks to support the
changes that we have made to md32_common.h. None of the assembly
implementations have been imported.

This makes supporting nmap easier.

Change-Id: Iae9241abdbc9021cc6bc35a65b40c3d739011ccc
Reviewed-on: https://boringssl-review.googlesource.com/7402
Reviewed-by: David Benjamin <davidben@google.com>