debug_tree: print out clique/base for MEM_REF/TARGET_MEM_REF

debug_tree: print out clique/base for MEM_REF/TARGET_MEM_REF

While debugging PR 122273, I noticed that print_node was not
printing out the clique/base for MEM_REF/TARGET_MEM_REF. This
made harder to understand why operand_equal_p (without looking
into the code) would be rejecting two looking the same MEM_REFs.

Changes since v1:
* v2: Don't print out clique/base if clique is 0.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* print-tree.cc (print_node): Print out clique/base
	for MEM_REF and TARGET_MEM_REF.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>