Deterministic build improvements

Deterministic build improvements

* configure.ac (BUILD_DETAILS): Rename from DETERMINISTIC_DUMP,
and negate its sense.  Use it via AC_SUBST, not AC_DEFINE,
and have its value be either empty or --no-build-details.
All uses changed.  Change option to --disable-build-details.
* doc/lispref/cmdargs.texi (Initial Options):
Document --no-build-details.
* doc/lispref/internals.texi (Building Emacs):
* etc/NEWS:
Document --disable-build-details.
* doc/lispref/intro.texi (Version Info): Say that
emacs-build-time can be nil.
* lisp/erc/erc-compat.el (erc-emacs-build-time):
Now nil if details are omitted.
* lisp/erc/erc.el (erc-cmd-SV):
* lisp/version.el (emacs-build-time):
Now nil if no build details.
(emacs-version):
Output build time only if build details.
* src/Makefile.in (BUILD_DETAILS): New macro.
(temacs, bootstrap-emacs): Use it.
* src/emacs.c (build_details): New var.
(standard_args, main): Support --no-build-details.
(Vdeterministic_dump): Remove; all uses replaced
by !build_details.
(syms_of_emacs): Set Vbuild_details to a boolean, not
to a Lisp_Object.
* src/lisp.h (build_details): New decl.
* src/sysdep.c (init_system_name): When !build_details,
set system-name to nil, not to "elided".