analyzer: support for creat, dup, dup2 and dup3 [PR106298]

analyzer: support for creat, dup, dup2 and dup3 [PR106298]

This patch extends the state machine in sm-fd.cc to support
creat, dup, dup2 and dup3 functions.

Lightly tested on x86_64 Linux.

gcc/analyzer/ChangeLog:
	PR analyzer/106298
	* sm-fd.cc (fd_state_machine::on_open): Add
	creat, dup, dup2 and dup3 functions.
	(enum dup): New.
	(fd_state_machine::valid_to_unchecked_state): New.
	(fd_state_machine::on_creat): New.
	(fd_state_machine::on_dup): New.

gcc/testsuite/ChangeLog:
	PR analyzer/106298
	* gcc.dg/analyzer/fd-1.c: Add tests for 'creat'.
	* gcc.dg/analyzer/fd-2.c: Likewise.
	* gcc.dg/analyzer/fd-4.c: Likewise.
	* gcc.dg/analyzer/fd-dup-1.c: New tests.

Signed-off-by: Immad Mir <mirimmad@outlook.com>