Add error codes for the platform module, to be used by
the setup \ terminate API.

Motivation is similar to NO_UDBL_DIVISION.

The alternative implementation of 64-bit mult is straightforward and aims at
obvious correctness. Also, visual examination of the generate assembly show
that it's quite efficient with clang, armcc5 and arm-clang. However current
GCC generates fairly inefficient code for it.

I tried to rework the code in order to make GCC generate more efficient code.
Unfortunately the only way to do that is to get rid of 64-bit add and handle
the carry manually, but this causes other compilers to generate less efficient
code with branches, which is not acceptable from a side-channel point of view.

So let's keep the obvious code that works for most compilers and hope future
versions of GCC learn to manage registers in a sensible way in that context.

See https://bugs.launchpad.net/gcc-arm-embedded/+bug/1775263

While the old name is explicit and aligned with the RFC, it's also very long,
so with the mbedtls_ prefix prepended we get a 31-char prefix to each
identifier, which quickly conflicts with our 80-column policy.

The new name is shorter, it's what a lot of people use when speaking about
that construction anyway, and hopefully should not introduce confusion at
it seems unlikely that variants other than 20/1305 be standardised in the
foreseeable future.

This implementation is based off the description in RFC 7539.

The ChaCha20 code is also updated to provide a means of generating
keystream blocks with arbitrary counter values. This is used to
generated the one-time Poly1305 key in the AEAD construction.

Test vectors are included from RFC 7539.

Poly1305 is also added to the benchmark program.

Add a function that deletes all the old Visual Studio prokect files
before generating the new ones. This ensure that project files for
delete example applications are removed from the repository.

When not running armcc, don't try to invoke armcc at all, not even to
report its version.

Warning: needs OpenSSL >= 1.1.1-pre1 installed and environment variable
OPENSSL_NEXT pointing to it.

Add mbedTLS.vcxproj to the VS2010 application template so that the next
time we auto-generate the application project files, the
LinkLibraryDependencies for mbedTLS.vcxproj are maintained.

Fixes #1347

Add MBEDTLS_ERR_XXX_HW_ACCEL_FAILED error codes for all cryptography
modules where the software implementation can be replaced by a hardware
implementation.

This does not include the individual message digest modules since they
currently have no way to return error codes.

This does include the higher-level md, cipher and pk modules since
alternative implementations and even algorithms can be plugged in at
runtime.