Bug #1450: Illumos should be buildable with GCC4
kernel inlines should support gcc 4
As a GCC extension, GCC used to define 'extern inline' to mean that a function was only ever emitted inline and no visible symbol was emitted. We rely on this for our inline ASM
C99, however, made 'extern inline' mean pretty much the reverse of this, and GCC 4.3 and above in C99 or GNU99 modes follow the standard, so we have to decorate each definition to indicate we want the non-standard behaviour.
This was going to be part of #1450, but I'm breaking it out to help the KVM folks.