How to use host compiler when cross compiling

[rossburton]

The built_tool example https://github.com/bfgroup/b2/tree/main/example/built_tool builds a tool that is then ran on the build machine to generate more code which is then compiled. In native builds this works as expected, but I can't see how this would work in a cross compile as the tool would be built with the cross-compiler, which the build machine cannot run.

How can I tell b2 that a particular target should be built with the host compiler, and not a cross compiler?