How to build/test glibc with new gcc

[Szabolcs Nagy <szabolcs dot nagy at arm dot com>]

i'm wondering what's the official way to build glibc with new gcc.

the documentation about building glibc assumes that the host
compiler is used when doing a native build, but if gcc is installed
at some prefix path, then the tests don't use the right libraries:

they use libgcc_s.so.1 and libstdc++.so.6 of the host (or fail
when the host does not have these).

Using LD_LIBRARY_PATH does not work as the tests override the
library path, but i assume this can be solved by either adding
-Wl,-rpath=/gcc/prefix/lib to the LDFLAGS of the tests or
copying the compiler runtime into the build path:

export PATH="/path/to/gcc-prefix/bin:$PATH"
cp -a /path/to/gcc-prefix/lib*/*.so* .
/path/to/glibc-src/configure --prefix=/usr
make -j
make check

is there a cleaner way to do it?