...by allowing our special @___... tokens anywhere within an install name,
so that external modules can configure --prefix=/@___... etc. This removes
the need for the special extshl and EXTRPATH=LOADER. Also, a new
OUT2BIN_NONE can be used for external modules where the generated libraries
need the default EXTRPATH=OOO, but generated executables are only used
during the build and such need RPATH=NONE.
Yeah, just build all the unneeded stuff (the executables like the
msgfmt command and their support libraries) in this case too, for
now. (We obviously won't be able to run ppc exectuables when
cross-compiling from Intel Mac.)
