as nigel says, they were provided originally to allow native Inferno
to be compiled on other operating systems.  (on Plan 9, to get a
cross-compiler you simply compile the compiler for the target with objtype set
for the host platform, and it's nearly that straightforward with the
Inferno variants under other operating systems, compiled by the host
system's compilers.)  we include all the libraries required to run the
compilers under a good range of operating systems, and also the source
for a portable version of mk, and a few other things.

in this latest Inferno package, i've put the utils directory in the free-ish source section.
since the source is provided, you can make them produce what you like.
they are simpler, and easier to port than gcc (any version) but typically produce better code
than lcc and are very quick.  as well as compiling Inferno, i have used them to cross-compile
Plan 9 libraries, kernels and applications on Solaris and FreeBSD, for
instance.   (you need some minor implants in the Plan 9 mkfiles.)
that's useful when you've got some target system you'd like
to run Plan 9, but the existing development environment is Windows or
a Unix system and you can't convert the organisation.