Provide cmacexp.

Provide cmacexp.
(c-macro-prompt-p): Renamed from c-macro-always-prompt-p.
(c-macro-cppflags): Var renamed from c-macro-default-cppflags.
(c-macro-expand): Don't handle C-u C-u specially.
Compute message here in var mymsg.
Clear buffer-auto-save-file-name.
(c-macro-display-buffer): Now takes no argument.
Use point-max to get large number.
(c-macro-default-message, c-macro-eval): Functions deleted.
(c-macro-expansion): Use startinstring as the char to insert.