analyzer: const functions have no side effects [PR104576]

analyzer: const functions have no side effects [PR104576]

PR analyzer/104576 tracks that we issue a false positive from
-Wanalyzer-use-of-uninitialized-value for the reproducers of PR 63311
when optimization is disabled.

The root cause is that the analyzer was considering that a call to
__builtin_sinf could have side-effects.

This patch fixes things by generalizing the handling for "pure"
functions to also consider "const" functions.

gcc/analyzer/ChangeLog:
	PR analyzer/104576
	* region-model.cc: Include "calls.h".
	(region_model::on_call_pre): Use flags_from_decl_or_type to
	generalize check for DECL_PURE_P to also check for ECF_CONST.

gcc/testsuite/ChangeLog:
	PR analyzer/104576
	* gcc.dg/analyzer/torture/uninit-pr63311.c: New test.
	* gcc.dg/analyzer/uninit-pr104576.c: New test.
	* gfortran.dg/analyzer/uninit-pr63311.f90: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>