automake: Support byte compilation in older Emacsen * lib/am/lisp.am (am__emacs_byte_compile_setup) [FIRST]: define new make variable, to use byte-compile-dest-file-function if available, else byte-compile-dest-file. (.el.elc): use it. * t/lisp-loadpath.sh: skip test if emacs version is <= 23, since their -L ordering is backwards. * NEWS: update.