[coreboot] What's the purpose of xcompile?

[Hamo]

Dear lists,
After review my cross-compiler patch, I found it does not work as
expect. We use a script called xcompile to set and verify the compile
toolchain. Must we use it? Can we just trust our users to let them set
their compiler prefix by themselves? If so, we can add cross-compiler
for ARM easily. If not, How could I add cross-compiler support to
xcompile? I just read the code when we supported PPC and alpha, but It
has changed a lot since then.

Thanks,
Hamo