cross-compile configure sizeof tests

[Tony Kimball]

libffi/configure  and libjava/configure use programs to test sizeof
(among other things, I would assume).  There must be a normal,
canonical method for handling this situation when cross-compiling,
used in other parts of gcc, but I have yet to find an example.
Hence my question:  Can someone point me to an example, and/or 
tell me explicitly how this situation is canonically treated?