This addresses

- request for improvement for faster key setup in RT#3576;
- clearing registers and stack in RT#3554 (this is more of a gesture to
see if there will be some traction from compiler side);
- more commentary around input parameters handling and stack layout
(desired when RT#3553 was reviewed);
- minor size and single block performance optimization (was lying around);

(Imported from upstream's 23f6eec71d)

This one is best reviewed by verifying that
23f6eec71dbd472044db7dc854599f1de14a1f48^ in upstream has the exact same
versions of these files (we had no local diffs), so we can just copy them
wholesale.

bssl speed reports a wash on my Mac. If I keep running it, different ones win
each time.

Change-Id: I729bd39cf0b3a30cc24de839e1c734dcaef972b8
Reviewed-on: https://boringssl-review.googlesource.com/4491
Reviewed-by: Adam Langley <agl@google.com>

This reverts the non-ARM portions of 97999919bb.
x86_64 perlasm already makes .globl imply .hidden. (Confusingly, ARM does not.)
Since we don't need it, revert those to minimize divergence with upstream.

Change-Id: I2d205cfb1183e65d4f18a62bde187d206b1a96de
Reviewed-on: https://boringssl-review.googlesource.com/3610
Reviewed-by: Adam Langley <agl@google.com>

We are leaking asm symbols in Android builds because the asm code isn't
affected by -fvisibility=hidden. This change hides all asm symbols.

This assumes that no asm symbols are public API and that should be true.
Some points to note:

In crypto/rc4/asm/rc4-md5-x86_64.pl there are |RC4_set_key| and
|RC4_options| functions which aren't getting marked as hidden. That's
because those functions aren't actually ever generated. (I'm just trying
to minimise drift with upstream here.)

In crypto/rc4/asm/rc4-x86_64.pl there's |RC4_options| which is "public"
API, except that we've never had it in the header files. So I've just
deleted it. Since we have an internal caller, we'll probably have to put
it back in the future, but it can just be done in rc4.c to save
problems.

BUG=448386

Change-Id: I3846617a0e3d73ec9e5ec3638a53364adbbc6260
Reviewed-on: https://boringssl-review.googlesource.com/3520
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

(Imported from upstream's 3e3cc471c2682f5cb40523f3997f75974de1755e.)

Change-Id: I8b6468b104091a609140a035739c09a031de90b4

(Imported from upstream's 2d4d9623da)

Improve CBC decrypt and CTR by ~13/16%, which adds up to ~25/33%
improvement over "pre-Silvermont" version. [Add performance table to
aesni-x86.pl].

(Imported from upstream's b347341c75)

(Imported from upstream's 5572bc4e2f)

This change adjusts the stack pointer during CBC decryption. The code
was previously using the red zone across function calls and valgrind
thinks that the "unused" stack is undefined after a function call.

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)