PR tree-optimization/37709                                              
	* tree.c (block_ultimate_origin): Move here from dwarf2out.             
	* tree.h (block_ultimate_origin): Declare.                              
	* dwarf2out.c (block_ultimate_origin): Move to tree.c                   
	* tree-ssa-live.c (remove_unused_scope_block_p):
	Eliminate blocks containig no instructions nor live variables nor
	nested blocks.
	(dump_scope_block): New function.
	(remove_unused_locals): Enable removal of dead blocks by default;
	enable dumping at TDF_DETAILS.

From-SVN: r144381