Drop the size arguments for the hash/equal functions stored in type
    descriptors.  Types know what size they are.  To make this work,
    generate hash/equal functions for types that can use an identity
    comparison but are not a standard size and alignment.
    
    Drop the multiplications by 33 in the generated hash code and the
    reflect package hash code.  They are not necessary since we started
    passing a seed value around, as the seed includes the hash of the
    earlier values.
    
    Copy the algorithms for standard types from the Go 1.7 runtime,
    replacing the C functions.
    
    Reviewed-on: https://go-review.googlesource.com/34983

From-SVN: r244256