Make 'make install' ignore the new 'fuzzterm' binary.
It's for regression testing and fuzzing, so there's no use for it if
you're not a developer working on the source.
Leaving it out of the 'make install' target in Makefile.gtk is no
trouble because that's already handled manually in Recipe by inserting
a giant hairy Makefile fragment to do the installation. But
Makefile.am was just setting bin_PROGRAMS to the full set of binaries
built, so for that one, I had to invent a new Recipe program category
[UT] which moves a particular binary into noinst_PROGRAMS.
While I was at it, I've retired the [M] program category, which has
been lying around unused since Ben's old Mac OS pre-X port.