Shouldn't I be able to set unrecognised target triples?

[Steven Stewart-Gallus]

Hello,

Currently I am experimenting with emscripten.  Currently I can
workaround everything by just setting the host target triple to
none-none-none.  However, it makes more sense to me to set the host
target triple to something like asmjs-unknown-emscripten.  I know the
GNU build system configure scripts don't understand that and would
logically have to act no differently than none-none-none if they could
understand that but I would like configure scripts to be able to
accept unknown host target triples so that my own scripts could read
the host_os, host_cpu and host_vendor options and autodetect default
settings to enable.  This way I could pass --host
asmjs-unknown-emscripten to my configure script and save passing a few
flags along the lines of --enable-emscripten-api.  This really isn't
important at all (I can manually pass a custom enable flag) but I was
just honestly surprised that Autoconf configure doesn't support this
and wondered why.

Thank you,
Steven Stewart-Gallus