Rename iterate to malloc_iterate internally.

I have no idea why I used the iterate name internally which is
completely unlike every other function name. Change this to match
everyone else so that it's now malloc_iterate everywhere.

This is probably the last chance to change this before mainline
modules begin, so make everything consistent.

Test: Compiles, unit tests passes.
Change-Id: I56d293377fa0fe1a3dc3dd85d6432f877cc2003c
diff --git a/libc/malloc_hooks/exported64.map b/libc/malloc_hooks/exported64.map
index 340106b..59ec1f0 100644
--- a/libc/malloc_hooks/exported64.map
+++ b/libc/malloc_hooks/exported64.map
@@ -7,13 +7,13 @@
     hooks_free_malloc_leak_info;
     hooks_get_malloc_leak_info;
     hooks_initialize;
-    hooks_iterate;
     hooks_mallinfo;
     hooks_malloc;
     hooks_malloc_backtrace;
     hooks_malloc_disable;
     hooks_malloc_enable;
     hooks_malloc_info;
+    hooks_malloc_iterate;
     hooks_malloc_usable_size;
     hooks_mallopt;
     hooks_memalign;