(cross-)compiling for biarch - where to put 32 bit headers?

[david dot hagood at gmail dot com]

I am cross-compiling GLIBC for 2 bi-arch systems (PPC/PPC64 and
X86/X86-64) and have a couple of questions on the generated headers.

1) When I have the library install its headers, by default both versions
want to write to ${SYSROOT}/usr/include. But that doesn't work as the 32
bit version installs different headers in the case of X86/X86-64 (changing
the definition of __WORDSIZE). What is the accepted install location for
32 bit headers in a GNU/Linux bi-arch system?

2) To change where the headers are installed, do I use the --with-headers,
or is that to change where the glibc compile process looks for headers?