Fixes related to CANNOT_DUMP mode, and a floating-point bug fix.

Fixes related to CANNOT_DUMP mode, and a floating-point bug fix.

Handle --version reasonably in CANNOT_DUMP configuration.
* src/emacs.c (emacs_version, emacs_copyright): New string
variables.
(Vemacs_version, Vemacs_copyright): New Lisp_Object variables.
(syms_of_emacs): Defvar them, and initialize them from the C
string variables.
(main): If initialization hasn't been done, print initial version
info from the C strings, instead of starting an interactive session.
* lisp/version.el (emacs-copyright, emacs-version): Don't define
here.
* configure.in: Look for version string in its new place.

* admin: Update scripts and text to refer to version number string in emacs.c
instead of version.el.

* src/emacs.c (main): Initialize initial-environment and process-environment
before generating from env, not after.

* src/lisp.h (XFLOAT_DATA): Use "0?x:x" to generate an rvalue. (bug#5916)
(LISP_MAKE_RVALUE) [!USE_LISP_UNION_TYPE && !__GNUC__]: Likewise.