Adds the Intel SHA opcodes sha1msg1, sha1msg2, sha1nexte, sha1rnds4, sha256msg1, sha256msg2, and sha256rnds2.
Opcodes have been checked against llvm-mc and binutils/gas/objdump.
Clients should not rely on binary compatibility of the added opcodes until both issues #3581 (closed) and #1312 have been closed.
Issue: #3581 (closed)