Remove volatile cast gyrations in strciphr.cpp (GH #1231)

It turns out we went down a rabbit hole when we added the volatile cast gyrations in an attempt to change the compiler behavior. We are seeing the same failures from AES, Rabbit, HIGHT, HC-128 and HC-256 with and without the gyrations.
We were able to work out the problems with Rabbit, HIGHT, HC-128 and HC-256. See GH #1231 and GH #1234.
We are also not able to successfully cut-in Cryptogams AES on ARMv7, so it is now disabled. See GH #1236.
Since the volatile casts were not a solution, we are backing it out along with associated comments.