tree-optimization/106722 - uninit analysis with long def -> use path

tree-optimization/106722 - uninit analysis with long def -> use path

The following applies similar measures as r13-2133-ge66cf626c72d58
to the computation of the use predicate when the path from PHI def
to use is too long and we run into compute_control_dep_chain limits.

It also moves the preprocessor define limits internal.

This resolves the reduced testcase but not the original one.

	PR tree-optimization/106722
	* gimple-predicate-analysis.h (MAX_NUM_CHAINS, MAX_CHAIN_LEN,
	MAX_POSTDOM_CHECK, MAX_SWITCH_CASES): Move ...
	* gimple-predicate-analysis.cc: ... here and document.
	(simple_control_dep_chain): New function, factored from
	predicate::use_cannot_happen.
	(predicate::use_cannot_happen): Adjust.
	(predicate::predicate): Use simple_control_dep_chain as fallback.

	* g++.dg/uninit-pr106722-1.C: New testcase.