Bootstrapping cross-toolchain for ia64

[Joseph Myers]

The current cleanest approach for bootstrapping cross toolchains for 
GNU/Linux targets is (following the guidance at 
<https://sourceware.org/ml/libc-alpha/2012-03/msg00960.html>):

* Build binutils.

* Install kernel headers.

* Build static-only, C-only GCC, configured so that inhibit_libc is 
defined, and using --with-glibc-version so things like stack-smashing 
protection are correctly configured without glibc headers being available.

* Build glibc, which should be identical to what you get from a longer 
sequence of alternating GCC and glibc builds (following fixes I made a few 
years ago for building like that with the initial bootstrap compiler).

* Build GCC with shared libraries and C++ support.

* If you want to run the glibc tests, you should reconfigure / rebuild 
with the new compiler to get everything required for all the tests.

This doesn't work for ia64 because libgcc depends on system headers even 
with inhibit_libc.  What's the cleanest approach (assuming recent-enough 
GCC and glibc) for building a cross toolchain for ia64-linux-gnu target, 
so I can make build-many-glibcs.py do whatever's necessary?

-- 
Joseph S. Myers
joseph@codesourcery.com