Improve readability of debug_tree() dumps for SSA_NAME and VECTOR_CST

Improve readability of debug_tree() dumps for SSA_NAME and VECTOR_CST

gcc/ChangeLog:

	* print-tree.c (print_node) [VECTOR_CST]: Coalesce the output of
	identical consecutive elements.
	[SSA_NAME]: Print the name's def stmt on its own line.  When printing
	the node's def stmt, avoid printing an unwanted trailing newline by
	replacing the call to print_gimple_stmt() with its inlined body and
	adjusting it to not set pp_needs_newline and to call pp_flush()
	instead of pp_newline_and_flush().

From-SVN: r239661