x86: Issue error for return/argument only with function body

x86: Issue error for return/argument only with function body

If we never generate function body, we shouldn't issue errors for return
nor argument.  Add silent_p to i386 machine_function to avoid issuing
errors for return and argument without function body.

gcc/

	PR target/99652
	* config/i386/i386-options.c (ix86_init_machine_status): Set
	silent_p to true.
	* config/i386/i386.c (init_cumulative_args): Set silent_p to
	false.
	(construct_container): Return early for return and argument
	errors if silent_p is true.
	* config/i386/i386.h (machine_function): Add silent_p.

gcc/testsuite/

	PR target/99652
	* gcc.dg/torture/pr99652-1.c: New test.
	* gcc.dg/torture/pr99652-2.c: Likewise.
	* gcc.target/i386/pr57655.c: Adjusted.
	* gcc.target/i386/pr59794-6.c: Likewise.
	* gcc.target/i386/pr70738-1.c: Likewise.
	* gcc.target/i386/pr96744-1.c: Likewise.