Vectorize fast path of _cpp_clean_line.

	* configure.ac (AC_C_BIGENDIAN, AC_TYPE_UINTPTR_T): New tests.
	(ssize_t): Check via AC_TYPE_SSIZE_T instead of AC_CHECK_TYPE.
	(ptrdiff_t): Check via AC_CHECK_TYPE.
	* config.in, configure: Rebuild.
	* system.h: Include stdint.h, if available.
	* lex.c (WORDS_BIGENDIAN): Provide default.
	(acc_char_mask_misalign, acc_char_replicate, acc_char_cmp,
	acc_char_index, search_line_acc_char, repl_chars, search_line_mmx,
	search_line_sse2, search_line_sse42, init_vectorized_lexer,
	search_line_fast): New.
	(_cpp_clean_line): Use search_line_fast.  Restructure the fast
	loop to make it clear when we're leaving the loop.  Stay in the
	fast loop for non-trigraph '?'.

Co-Authored-By: Andi Kleen <ak@linux.intel.com>
Co-Authored-By: David S. Miller <davem@davemloft.net>

From-SVN: r163446