SHA-2 code does not compile on FreeBSD

SHA-2 code does not compile on FreeBSD

The code fails to compile with the below error:
qcryptographichash.cpp:55: error: conflicting declaration 'typedef quint64 uint64_t'
/usr/include/sys/types.h:99: error: 'uint64_t' has a previous declaration as 'typedef __uint64_t uint64_t'

FreeBSDs types.h defines the used defines. Maybe it would be less
ugly to switch the code to quint*, or use a define to do so, or to
have basic os detection for stdint.h, not to include sys/types.h.

Change-Id: Ic62ae4b742c1123b4b7e17158d216374e609f59f
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>