Add missing assembly files to CMake and generator script

[cmcgee1024]

Update both the CMakeLists.txt for CCryptoBoringSSL and the CMakeLists.txt generator so that it can add platform-independent assembly files.

Checklist

• I've run tests to see all new and existing tests pass
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary

If you've made changes to gyb files

• I've run ./scripts/generate_boilerplate_files_with_gyb and included updated generated files in a commit of this pull request

Motivation:

There are downstream linker failures due to missing symbols from certain platform neutral assembly files.

Modifications:

The scripts/update-cmake-lists.sh has an updated find expression to discover platform-independent assembly files and includes them in the CMakeLists.txt files.

Result:

There will be more symbols included from third-parties such as BoringSSL.