HEADS UP: COMPAT_IA32 renamed COMPAT_FREEBSD32

[Nathan Whitehorn]

Starting with revision 206336, the kernel option COMPAT_IA32, used for 
compatibility with i386 binaries on amd64 and ia64 systems, has been 
renamed to COMPAT_FREEBSD32, in analogy to COMPAT_LINUX32. This follows 
the same change in HEAD a month ago. As such, all kernel configurations 
with this option need to be updated when updating to 8-STABLE past this 
revision.

This change allows MFCs of recent improvements to the 32-bit 
compatibility after the addition of 32-bit compatibility for non-x86 
platform in -CURRENT.
-Nathan