${_EMACS_VERSION_MAJOR} and ${_EMACS_VERSION_MINOR} to determine installed
version of emacs.
Also, set minimum version of _EMACS_REQD to the same as
${_EMACS_VERSION_MAJOR}.${_EMACS_VERSION_MINOR}. Otherwise, buildlink
does not work for emacs lisp libraries.
Should fix PR/42763.
created or not. Packages that include other ELP's buildlink3.mk must define
EMACS_BUILDLINK. Other packages don't create wrappers, which reduces build
time a lot.
Don't call pkg_info to get the installed Emacs version; always use the
version matching EMACS_TYPE set by users. Be DEPENDS to it. This should
address pkg/37146 by Aleksey Cheusov.
While here convert some emacs lisp packages to user-destdir.