[ofw] why does ibat build so slowly?

[Sean Hefty]

>IBAT is a user mode component while most of the stack is kernel mode.
>
>When the compiler has to compile it, it looks at a different set of
>include files.
>This means that it has to read them all from the disk (probably not in
>the cache).
>The time that it takes to read all the files (seek time of disk) is what
>it takes long to compile.
>
>This is also true for other user mode components such as opensm.

I've pretty much permanently removed opensm from my typical build.  It's
painful.  :)  (It takes me as long to build opensm as it does the entire rest of
the tree.)

IBAT is built after al and complib, both of which have usermode components, so
I'm not sure caching is the issue.  There's just a definite noticeable hang when
the build hits ibat.  Maybe it's just a display issue and ibat looks like the
problem, but wsdinstall has a similar hang, and it too has
$(PLATFORM_SDK_PATH)\include in its include path.

- Sean