Compares whether region_a is equivalent to region_b. null as an argument is equal to itself, but not to any non-null region.
a #cairo_region_t or null
true if both regions contained the same coverage, false if it is not or any region is in an error status.
Compares whether region_a is equivalent to region_b. null as an argument is equal to itself, but not to any non-null region.