Extend emconfigure/emmake with setting CC_BUILD / CXX_BUILD

[vadimkantorov]

Must point to host compilers in some build toolchains...

[sbc100]

Any improvments to these scripts would be most welcome.

Note that I believe the there system currently works fairly differently in that emcmake declares emcc as a cross compiler, but emconfigure I believe tricks autoconf into thinking that emcc is the host compiler (i.e. doesn't run in cross compilation mode at all). At least that is how I remember it working last time I looked into it.

Another question I would have is, what value would be pick for the build-machine compiler? We don't really know what the idea value is for this do we?

[vadimkantorov]

The problem with such approach is that some dependencies must be provided with proper host compiler (like fontconfig), but are not using it if formal host/build are identical...

[vadimkantorov]

It also appears that autotools configure scripts do not have a way to provide host/build triplets via environment variables...