If `CMAKE_INSTALL_BINDIR` is a different absolute path per project, as it is with NixOS when we install every package to its own prefix, the old way fails when the absolute path gets prepended with `CMAKE_INSTALL_PREFIX`. Call the adjusted variable `outpath_abs` instead of `binpath` since it isn't always an executable being symlinked into place. Also fix one stray `bin` -> `CMAKE_INSTALL_LIBDIR`

If `CMAKE_INSTALL_BINDIR` is a different absolute path per project, as it is with NixOS when we install every package to its own prefix, the old way fails when the absolute path gets prepended with `CMAKE_INSTALL_PREFIX`. Using `extend_path` from the install-time script isn't really possible, so we just make the caller responsible for making the path absolute instead. Also fix one stray `bin` -> `CMAKE_INSTALL_BINDIR`

If `CMAKE_INSTALL_BINDIR` is a different absolute path per project, as it is with NixOS when we install every package to its own prefix, the old way fails when the absolute path gets prepended with `CMAKE_INSTALL_PREFIX`. Call the adjusted variable `outpath_abs` instead of `binpath` since it isn't always an executable being symlinked into placeUsing `extend_path` from the install-time script isn't really possible, so we just make the caller responsible for making the path absolute instead. Also fix one stray `bin` -> `CMAKE_INSTALL_LIBBINDIR`