tools lib rbtree: Pick some improvements from the kernel rbtree code

The tools/lib/rbtree.c code came from the kernel, removing the
EXPORT_SYMBOL() that make sense only there, unfortunately it is not
being checked with tools/perf/check_headers.sh, will try to remedy this,
till then pick the improvements from:

b0687c1119b4e8c8 ("lib/rbtree: use '+' instead of '|' for setting color.")

That I noticed by doing:

diff -u tools/lib/rbtree.c lib/rbtree.c
diff -u tools/include/linux/rbtree_augmented.h include/linux/rbtree_augmented.h

There is one other cases, but lets pick it in separate patches.

Cc: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Noah Goldstein <[e-mail]>
Link: https://lore.kernel.org/lkml/ZigZzeFoukzRKG1Q@x1
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/include/linux/rbtree_augmented.h

···
 
 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 {
-	rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
+	rb->__rb_parent_color = rb_color(rb) + (unsigned long)p;
 }
 
 static inline void rb_set_parent_color(struct rb_node *rb,
 				       struct rb_node *p, int color)
 {
-	rb->__rb_parent_color = (unsigned long)p | color;
+	rb->__rb_parent_color = (unsigned long)p + color;
 }
 
 static inline void

tools/lib/rbtree.c

···
 
 static inline void rb_set_black(struct rb_node *rb)
 {
-	rb->__rb_parent_color |= RB_BLACK;
+	rb->__rb_parent_color += RB_BLACK;
 }
 
 static inline struct rb_node *rb_red_parent(struct rb_node *red)