Bugfix: Add used field to MD5 hash state

MD5.jl currently uses undocumented and unexported internals of the SHA stdlib.
PR #86 to SHA.jl added a new field, `used` to the SHA states. Since MD5 uses
internal SHA functions which now look for this field, MD5 tests began to fail.

This PR adds the needed `used` field, so MD5 now runs. The real fix is to not
rely on SHA internals.

Project.toml

@@ -1,6 +1,6 @@
 name = "MD5"
 uuid = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
-version = "0.2.1"
+version = "0.2.2"
 
 [deps]
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"

src/types.jl

@@ -2,17 +2,14 @@ mutable struct MD5_CTX <: SHA_CTX
     state::Array{UInt32,1}
     bytecount::UInt64
     buffer::Array{UInt8,1}
+    used::Bool
 end
 
 digestlen(::Type{MD5_CTX}) = 16
 state_type(::Type{MD5_CTX}) = UInt32
 # blocklen is the number of bytes of data processed by the transform!() function at once
 blocklen(::Type{MD5_CTX}) = UInt64(64)
 
-
-
-
-MD5_CTX() = MD5_CTX(copy(MD5_initial_hash_value), 0, zeros(UInt8, blocklen(MD5_CTX)))
+MD5_CTX() = MD5_CTX(copy(MD5_initial_hash_value), 0, zeros(UInt8, blocklen(MD5_CTX)), false)
 Base.copy(ctx::T) where {T<:MD5_CTX} = T(copy(ctx.state), ctx.bytecount, copy(ctx.buffer))
 Base.show(io::IO, ::MD5_CTX) = write(io, "MD5 hash state")
-