[Http-crcsync] Switch to APR SHA1 implementation

[Alex Wulms]

Hi,

I have talked with a few Apache developers at FOSDEM today. They advised
me to use the SHA1 implementation in the APR libraries. Doing so removes
the dependency on libcrypt, increasing the chance of getting the modules
included in the Apache core distribution (as of Apache 2.4).

Code is meanwhile adapted and checked-in. I also fixed two small bugs.
See the code in the repository for more details.


Cheers,
Alex