dca: Do not check for Const on the left hand side of And/Or.
iropt: Use new_ir_node() instead of strange combination of exact_copy() and changing inputs.

Also call optimize_node() instead of only calling transform_node_*() or doing nothing.
ir: Add and use new_similar_node().
ia32: Do not use current_ir_graph in ia32_gen_Unknown().
ia32: Pass an ir_graph* to ia32_immediate_from_long() instead of using current_ir_graph.
ia32: Use get_Block_irg() instead of current_ir_graph.
ia32: Pass an ir_graph* to get_global_base() instead of using current_ir_graph.
ia32: Replace duplicate use of get_irg_frame().
be: Pass an ir_graph* to the arch_pretrans_nodes callback instead of using current_ir_graph.
irscc: Remove a probably erroneous use of current_ir_graph in free_loop_information().

There is an explicit irg available here.
irhooks: Remove the parameter ir_graph* from hook_new_node.

It is unused and anyway redundant due to the given ir_node*.
loop: Use the given irg, not current_ir_graph.
stat: Do not use current_ir_graph.
Fixed local optimization: A-X == A -> X == 0.

This fixes opt/fehler235.c.
iropt: Check symmetric case of a op b == a, if this case failed.