Faster, more compact, and readable closure creation

Faster, more compact, and readable closure creation

Simplify closure creation by calling a single function at run time
instead of putting it together from small pieces.  This is faster
(by about a factor 2), takes less space on disk and in memory, and
makes internal functions somewhat readable in disassembly listings again.

This is done by creating a prototype function at compile-time whose
closure variables are placeholder values V0, V1... which can be seen
in the disassembly.  The prototype is then cloned at run time using
the new make-closure function that replaces the placeholders with
the actual closure variables.

* lisp/emacs-lisp/bytecomp.el (byte-compile-make-closure):
Generate call to make-closure from a prototype function.
* src/alloc.c (Fmake_closure): New function.
(syms_of_alloc): Defsubr it.
* src/data.c (syms_of_data): Defsym byte-code-function-p.