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_debug/exported32.map b/libc/malloc_debug/exported32.map
index 8ed37fa..f75d173 100644
--- a/libc/malloc_debug/exported32.map
+++ b/libc/malloc_debug/exported32.map
@@ -8,13 +8,13 @@
     debug_free_malloc_leak_info;
     debug_get_malloc_leak_info;
     debug_initialize;
-    debug_iterate;
     debug_mallinfo;
     debug_malloc;
     debug_malloc_backtrace;
     debug_malloc_disable;
     debug_malloc_enable;
     debug_malloc_info;
+    debug_malloc_iterate;
     debug_malloc_usable_size;
     debug_mallopt;
     debug_memalign;