VFP context switching

VFPSupport update, for anyone watching this thread.

VFPSupport has now been updated to support the Cortex-A7 (e.g. Raspberry Pi 2) and Cortex-A15 (e.g. OMAP5). Both of these platforms lack hardware support for VFP ‘short vectors’, and so VFPSupport will provide a software emulation of the functionality (albeit at much worse performance). In fact, while testing things I realised that Cortex-A9 lacks hardware support for short vectors as well, so I’ve enabled the software emulation for that hardware as well.

To help programmers work out whether short vectors are implemented in hardware, software, or neither, VFPSupport_Features 2 can now return that information. Note that with the current version of VFPSupport it’s guaranteed that all hardware will at least have software support for short vectors, but that doesn’t mean things won’t change in the future!