* config/s390/s390.md (movstrdix_64, movstrsix_31, movstrdi_64,
	movstrsi_31, clrstrsi_64, clrstrsi_31): Improve RTL templates.
	(clrstrdi, clrstrsi): Adapt callers.

	(extendsidi2, zero_extendsidi2): Remove no-conflict blocks.

	(movti splitter): Never use register 0 as base register.

From-SVN: r48832