Identified with misc-static-assert.
This patch eliminates pesky "No newline at end of file" messages from git diff.
Adds an *unaudited* SHA-256 implementation to `llvm/Support`. The ongoing lld-macho effort needs this to emit an adhoc code signature for macho files on macOS Big Sur. Reviewed By: mehdi_amini Differential Revision: https://reviews.llvm.org/D96540