re PR rtl-optimization/90257 (8% degradation on cpu2006 403.gcc starting with r270484)

re PR rtl-optimization/90257 (8% degradation on cpu2006 403.gcc starting with r270484)

	PR rtl-optimization/90257
	* cfgrtl.c (flow_active_insn_p): Return true for USE of a function
	return value.

	Revert the revert:
	2019-04-21  H.J. Lu  <hongjiu.lu@intel.com>

	PR target/90178
	Revert:
	2018-11-21  Uros Bizjak  <ubizjak@gmail.com>

	Revert the revert:
	2013-10-26  Vladimir Makarov  <vmakarov@redhat.com>

	Revert:
	2013-10-25  Vladimir Makarov  <vmakarov@redhat.com>

	* lra-spills.c (lra_final_code_change): Remove useless move insns.

From-SVN: r270653