Include quotearg.h immediately after config.h.

Include quotearg.h immediately after config.h.
No need to include stddef.h or sys/types.h any more.
Surround local include files with "", not "<>".
Assume HAVE_LIMITS_H unconditionally, as we assume C89.
Similarly, assume HAVE_C_BACKSLASH_A, CHAR_BIT, UCHAR_MAX, UINT_MAX,
HAVE_STDLIB_H, HAVE_STRING_H, STDC_HEADERS.
(HAVE_MBSINIT): Undef if !HAVE_MBRTOWC.
(mbsinit): Define to 1 if !defined mbsinit && !HAVE_MBSINIT.
(ISPRINT): Remove; no longer needed now that we assume C89.

(clone_quoting_options, quotearg_buffer, quotearg_n_options):
Preserve errno.

(quotearg_buffer_restyled, quotearg_n, quotearg_n_style,
quotearg_char): Use SIZE_MAX rather than
(size_t) -1 when we are talking about "infinity".

(quotearg_buffer_restyled): Fix bug when quoting trigraphs.