bug#5167: maximum command-line length assumed in Makefiles

[Glenn Morris]

lisp/Makefile.in's compile-main rule passes a huge command-line to a
recursive make. The exact length depends on the full path to the build
directory. Eg it is 70676 characters for me.

Since it includes the full path to every single lisp file, it must be
longer than src/Makefile.in's $lisp variable, which only includes some
of them. Therefore if the lisp/Makefile rule works on all the
platforms supported by Emacs, there is no longer any need for the
separate $shortlisp variable in src/Makefile.in, which exists only to
prevent the command-line getting too long on "some platforms".

Depending on whether the above is true or not, this is either a
wishlist or a normal bug.