Why is $prefix/include not inside cpp searchpath?

[Per Bothner]

Martin Kahlert wrote:

>Hi!
>
>I checked out yesterday's gcc version and found that jni.h is not
>found any more although it's there:
>
See http://gcc.gnu.org/ml/gcc-patches/2001-09/msg00519.html
for a patch.

I don't know if $prefix/include has ever been in the search path, at
least not for a long time.

I'm surprised to note there have been *no* substantive feedback on the
patch - only some discussion on updating the documentation.  I thought
it would be more controversial.

	--Per