invoke.texi (ssa-name-def-chain-limit): Document new --param.

gcc/ChangeLog:

	* doc/invoke.texi (ssa-name-def-chain-limit): Document new --param.
	* params.def (PARAM_SSA_NAME_DEF_CHAIN_LIMIT): Add new --param.
	* tree-vrp.c (vrp_prop::check_mem_ref): Use
	PARAM_SSA_NAME_DEF_CHAIN_LIMIT.

gcc/testsuite/ChangeLog:

	* gcc.dg/Warray-bounds-43.c: New test.

From-SVN: r273454