Default installation directory for include files when cross compiling

[Gabriel Dos Reis]

On Fri, 16 Jun 2006, Mark Mitchell wrote:

| > The default, when it was done, was for common cases: native builds.
| > It was mostly done for matching the way other libraries are built and
| > installed.
|
| It is OK to leave the default as is for native builds.  However, the
| default for cross builds should be changed.

OK.

-- Gaby