Rust builds (custom build.rs and gcc-rs users) expect to have the
compiler and the linker available to them as a single command with no
white space trailing. Yocto unfortunately does not conform to that. The
build compiler and linker almost always have a trailing space due to
how the variables are composed and the target compiler and linker are
almost always more than a single command. Then if you throw ccache into
the mix you'll get another command. As a result to handle all these
cases properly there need to be wrappers created. This change creates
wrappers for both build and target and both the linker and compiler.
This likely fixes#76.
Provide documentation behind what the triples mean for Yocto and Rust
since they have different meanings of BUILD, TARGET, and HOST. Namely
Rust uses HOST when Yocto means BUILD. In our current supported cases
HOST and TARGET from Yocto mean the same thing.
Doug Goldstein