I am trying to decode "configure" script for "bluez" package as far as how are "configure" options for cross-compiling passed to libtoool or GCC to build C++ library.
As far as I can tell the "configure" triplet analysis (case) has no options to analyze anything with "linux" in it ,therefore I always end up with C++ library of --build on default architecture.
./configure is a machine-generated script, your time might be better spent looking at the file used to generate it, usually configure.ac or configure.in. It will hopefully give you a better impression of the intent behind the script.