* configure.in (LIMITS_INC_SRCDIR): New variable.
	* configure.target (LIMITSH): New variable.
	* porting.texi: Discuss numeric limits.
	* config/cpu/generic/bits/limits.h: New file.
	* config/cpu/i386/bits/limits.h: New file.
	* include/Makefile.am: Install bits/limits.h.
	* include/bits/c++config: Include bits/limits.h.

From-SVN: r44877