Imports of package codesign

PathSynopsis
crypto/sha256Package sha256 implements the SHA224 and SHA256 hash algorithms as defined in FIPS 180-4.
debug/machoPackage macho implements access to Mach-O object files.
encoding/binaryPackage binary implements simple translation between numbers and byte sequences and encoding and decoding of varints.
ioPackage io provides basic interfaces to I/O primitives.