Re-add dlmalloc for 32 bit.

It turns out that appportable has a version that calls dlmalloc directly.
Re-add the dlmalloc symbol for 32 bit only as a compatibility shim that
calls malloc.

Bug: 17881362
Change-Id: I8f20963b0b8d323489dc083e4063779e0d1d7447
diff --git a/libc/bionic/ndk_cruft.cpp b/libc/bionic/ndk_cruft.cpp
index 829e8f3..7600817 100644
--- a/libc/bionic/ndk_cruft.cpp
+++ b/libc/bionic/ndk_cruft.cpp
@@ -320,4 +320,10 @@
   return malloc_usable_size(ptr);
 }
 
+// Older versions of appportable used dlmalloc directly instead of malloc,
+// so export this compatibility shim that simply calls malloc.
+extern "C" void* dlmalloc(size_t size) {
+  return malloc(size);
+}
+
 #endif