[build2] guess C compiler type

[Boris Kolpackov]

> Moldmann Max <MoldmannMax at JohnDeere.com> writes:
> 
> C:\Tools\c166VXv3.0r3/bin/cc166.exe --version
> TASKING VX-toolset for C166: control program   v3.0r3 Build 128
> Copyright 2004-2011 Altium BV

What does your compiler print with -v? That is:

> C:\Tools\c166VXv3.0r3/bin/cc166.exe -v