edit: do not enable multiline mode with no editor active

If neither gmacs/emacs nor vi are active, the multiline mode should
not be enabled even if the multiline option is on. Doing so can
cause inconsistent behaviour, particularly in multibyte locales
where, if the shell is compiled with SHOPT_RAWONLY (as is default),
the no-editor mode is actually handled by vi.c.

Also, the new --histreedit and --histverify options only work in
the emacs or vi editors, or in no-editor mode when handled by vi.
Which means they cannot ever work if neither emacs or vi were
compiled in (i.e. SHOPT_ESH and SHOPT_VSH were both disabled).
In that case, there's no point in compiling in those options.
Come to think of it, the same applies to the multiline option.

All changed files:
- Update SHOPT_ESH/SHOPT_VSH preprocessor directives as per above.

src/cmd/ksh93/include/defs.h,
src/cmd/ksh93/include/shell.h:
- Move definitions of history expansion-related options to shell.h,
  which is where all the other shell options are defined.

src/cmd/ksh93/include/edit.h

@@ -135,7 +135,9 @@ typedef struct edit
 	int	e_stkoff;	/* saved stack offset */
 	char	**e_clist;	/* completion list after <ESC>= */
 	int	e_nlist;	/* number of elements on completion list */
+#if SHOPT_ESH || SHOPT_VSH
 	int	e_multiline;	/* allow multiple lines for editing */
+#endif
 	int	e_winsz;	/* columns in window */ 
 	Edpos_t	e_curpos;	/* cursor line and column */
 	Namval_t *e_default;	/* variable containing default value */