Tree inlining, tested with no regressions, builds working libgcj on
i686-linux-gnu.

It's not yet perfectly integrated into the compiler in that it's still
sensitive to the order in which methods are compiled.  However, even
with that limitation it's still useful.  This can be fixed at some
later date by reorganizing the way that gcj does things and deferring
code generation until we have trees for everything.

Also, it's only hooked into the source compiler.

This patch fixes a performance regression that was caused by the RTL
inliner being disabled.

Andrew.