build: Move the Emacs package sources to subdirectory gettext-tools/emacs/.
* gettext-tools/emacs/*.el: Moved here from gettext-tools/misc/.
* gettext-tools/emacs/Makefile.am: New file, based on
gettext-tools/misc/Makefile.am.
* gettext-tools/misc/Makefile.am (lisp_LISP): Remove variable.
* gettext-tools/configure.ac (AC_CONFIG_FILES): Add emacs/Makefile.
* gettext-tools/Makefile.am (SUBDIRS): Add 'emacs'.
