radix tree test suite: Remove types.h

Move the pieces we still need to tools/include and update a few implicit
includes.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
diff --git a/tools/testing/radix-tree/linux.c b/tools/testing/radix-tree/linux.c
index c27c112..93f0661 100644
--- a/tools/testing/radix-tree/linux.c
+++ b/tools/testing/radix-tree/linux.c
@@ -5,6 +5,7 @@
 #include <unistd.h>
 #include <assert.h>
 
+#include <linux/gfp.h>
 #include <linux/poison.h>
 #include <linux/slab.h>
 #include <linux/radix-tree.h>