tree: Canonical order for ADDR

tree: Canonical order for ADDR

This is the followup based on the review at
https://inbox.sourceware.org/gcc-patches/CAFiYyc3xeG75dsWaF63Zbu5uELPEAEoHwGfoGaVyDWouUJ70Mg@mail.gmail.com/
.
We should put ADDR_EXPR last instead of just is_gimple_invariant_address ones.

Note a few match patterns needed to be updated for this change but we get a decent improvement
as forwprop-38.c is now able to optimize during CCP rather than taking all the way to forwprop.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* fold-const.cc (tree_swap_operands_p): Put ADDR_EXPR last
	instead of just is_gimple_invariant_address ones.
	* match.pd (`a ptr+ b !=\== ADDR`, `ADDR !=/== ssa_name`):
	Move the ADDR to the last operand. Update comment.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>