gnulib, the implementation goes back to the AMD Software Optimizer
guide. A number of platforms will want to replace the C version with
assembler code using native instructions.
The algorithm used is the Jenkins hash. The name (mi_vector_hash)
reflects the nature of the hash function.
Add glue for libc ATF tests and include a test case to make sure that
(mis)alignment and endianess are handled correctly.
Bump libc minor to 169.