Default to disabling the linker warnings about execstack and RWX segments if the...

Default to disabling the linker warnings about execstack and RWX segments if the target is the HPPA architecture.

	PR 29263
	* configure.ac (ac_default_ld_warn_execstack): Default to 'no' for
	HPPA targets.
	(ac_default_ld_warn_rwx_segments): Likewise.
	* configure: Regenerate.
	* testsuite/ld-elf/elf.exp: Add the --warn-execstack command line
	option to the command line when running execstack tests for the
	HPPA target.