radix tree test suite: Enable address sanitizer

I was looking for a memory scribble and instead found a pile of memory
leaks.  Ensure no more occur in future.
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Rehas Sachdeva <aquannie@gmail.com>

tools/testing/radix-tree/Makefile

 
-CFLAGS += -I. -I../../include -g -O2 -Wall -D_LGPL_SOURCE
+CFLAGS += -I. -I../../include -g -O2 -Wall -D_LGPL_SOURCE -fsanitize=address
 LDFLAGS += -lpthread -lurcu
 TARGETS = main idr-test multiorder
 CORE_OFILES := radix-tree.o idr.o linux.o test.o find_bit.o