This adds all the relevant bits and pieces to add a `shgemv` path as
well as a future `hgemm`/`hgemv` path in a similar model to `sb` and `b`
interfaces.
I've also fixed a few bits and pieces around `shgemm` which didn't build
in a few situations.
This fixes an issue originally introduced with the BGEMM kernel.
I've updated the tests to run with `beta=1.0` so as to test loading and
updating from C.
Alongside this, the tests now return sensible return values to reduce
the risk of them being ignored.
Also fixed a bug in `generic/gemv_t.c` resulting in weird outputs for
`bgemv`.
- Sets up all the various entrypoints for `bgemv`
- Adds `bscal` for use in the `bgemv` interface
- Adds test cases for comparing `sgemv` and `bgemv`
- Adds generic kernels for `bgemv_n` and `bgemv_t` which are accurate
enough to pass above tests
