Fix CPU speed detection for Bulldozer and related cores.

It seems that our SSE-based speed test is 1 IPC (instructions per clock)
on all current CPUs, and 1.4 IPC on the Bulldozer, which leads to its
result being 40% too high. Correct that in the function.
Fixed a detection for Turion Griffin - it's ext_family is not 23, it's 17.

Also, the sse-width guesswork seems to handle this (wrong) Griffin ext_family
explicitly, so fix it there as well.

Seems that members of ext_family 20 (AMD Fusion based APUs) also are 64-bit,
but they have the authoritative sse width detection bit, so we don't need
to handle them explicitly here.
Simplify Bulldozer detection; differentiate Bulldozer<->Vishera.

Also add two tests:
- AMD FX-8150 - which is decoded as 'Bulldozer X4'
- AMD FX-9590 - which is decoted as 'Vishera X4'