Refactor the malloc_info code.

malloc_info needs to be per native allocator, but the code treated it
like a global function that doesn't depend on the native memory allocator.

Update malloc debug to dump the actual pointers that it has been tracking.

Test: bionic-unit-tests pass.
Test: malloc debug tests pass.
Test: malloc hook tests pass.
Change-Id: I3b0d4d748489dd84c16d16933479dc8b8d79013e
Merged-In: I3b0d4d748489dd84c16d16933479dc8b8d79013e
(cherry picked from commit a3656a98b10d2a4a6194a5d9705ad9c2cc5877b0)
diff --git a/libc/malloc_hooks/exported64.map b/libc/malloc_hooks/exported64.map
index 72465c4..340106b 100644
--- a/libc/malloc_hooks/exported64.map
+++ b/libc/malloc_hooks/exported64.map
@@ -13,6 +13,7 @@
     hooks_malloc_backtrace;
     hooks_malloc_disable;
     hooks_malloc_enable;
+    hooks_malloc_info;
     hooks_malloc_usable_size;
     hooks_mallopt;
     hooks_memalign;