perf: Handle new rbtree implementation

perf: Handle new rbtree implementation

Perf build fails with the new rbtree implementation:

  ../../lib/rbtree.c:24:36: fatal error: linux/rbtree_augmented.h: No such file or directory compilation terminated.

Fix by updating the Makefile and adding a btree_augmented.h
wrapper.

Reported-and-tested-by: Borislav Petkov <[email protected]>
Signed-off-by: Markus Trippelsdorf <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Borislav Petkov <[email protected]>
Link: http://lkml.kernel.org/r/20121009180156.GA245@x4
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>