analyzer: directly explore within static functions [PR93355,PR96374]

analyzer: directly explore within static functions [PR93355,PR96374]

PR analyzer/93355 tracks that -fanalyzer fails to report the FILE *
leak in read_alias_file in intl/localealias.c.

One reason for the failure is that read_alias_file is marked as
"static", and the path leading to the single call of
read_alias_file is falsely rejected as infeasible due to
PR analyzer/96374.  I have been attempting to fix that bug, but
don't have a good solution yet.

Previously, -fanalyzer only directly explored "static" functions
if they were needed for call summaries, instead forcing them to
be indirectly explored, but if we have a feasibility bug like
above, we will fail to report any issues in a function that's
only called by such a falsely infeasible path.

It now seems wrong to me to reject directly exploring static
functions: even if there is currently no way to call a function,
it seems reasonable to warn about bugs within them, since
otherwise these latent bugs are a timebomb in the code.

Hence this patch reworks toplevel_function_p to directly explore
almost all functions, working around these feasiblity issues.
It introduces a naming convention that "__analyzer_"-prefixed
function names don't get directly explored, since this is
useful in the analyzer's DejaGnu-based tests.

This workaround gets PR analyzer/93355 closer to working, but
unfortunately there is a second instance of PR analyzer/96374
within read_alias_file itself which means even with this patch
-fanalyzer falsely rejects the path as infeasible.

Still, this ought to help in other cases, and simplifies the
implementation.

gcc/analyzer/ChangeLog:
	PR analyzer/93355
	PR analyzer/96374
	* engine.cc (toplevel_function_p): Simplify so that
	we only reject functions with a "__analyzer_" prefix.
	(add_any_callbacks): Delete.
	(exploded_graph::build_initial_worklist): Update for
	dropped param of toplevel_function_p.
	(exploded_graph::build_initial_worklist): Don't bother
	looking for callbacks that are reachable from global
	initializers.

gcc/testsuite/ChangeLog:
	PR analyzer/93355
	PR analyzer/96374
	* gcc.dg/analyzer/conditionals-3.c: Add "__analyzer_"
	prefix to support subroutines where necessary.
	* gcc.dg/analyzer/data-model-1.c: Likewise.
	* gcc.dg/analyzer/feasibility-1.c (called_by_test_6a): New.
	(test_6a): New.
	* gcc.dg/analyzer/params.c: Add "__analyzer_" prefix to support
	subroutines where necessary.
	* gcc.dg/analyzer/pr96651-2.c: Likewise.
	* gcc.dg/analyzer/signal-4b.c: Likewise.
	* gcc.dg/analyzer/single-field.c: Likewise.
	* gcc.dg/analyzer/torture/conditionals-2.c: Likewise.