along the same line of thought as legacy/trac#24363, literally nobody needs to run `setenv LD_LIBRARY_PATH /usr/athena/lib` anymore. hell, basically nobody runs `setenv` at all anymore. Also, does anybody actually statically compile tor using the method specified? I would assume that most people use the distro packages. even TB doesn't compile static, at least on Linux. I figure we can dump everything but the first two paragraphs, and maybe add a reference to doc/building-tor-* (legacy/trac#26376).