Hide dlmalloc symbols.

We need to leave dlmalloc_trim and dlmalloc_inspect_all exposed for
the VM, but if we're seriously looking at other malloc implementations,
that's something we're going to have to fix.

Bug: 11156955
Change-Id: If85156c280044f1616c09a3c50ba674aaf0e8d3a
diff --git a/libc/bionic/dlmalloc.c b/libc/bionic/dlmalloc.c
index 3a615d2..2d67392 100644
--- a/libc/bionic/dlmalloc.c
+++ b/libc/bionic/dlmalloc.c
@@ -46,14 +46,11 @@
   *((int**) 0xdeadbaad) = (int*) address;
 }
 
-static void* named_anonymous_mmap(size_t length)
-{
-    void* ret;
-    ret = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
-    if (ret == MAP_FAILED)
-        return ret;
-
-    __bionic_name_mem(ret, length, "libc_malloc");
-
-    return ret;
+static void* named_anonymous_mmap(size_t length) {
+  void* map = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+  if (map == MAP_FAILED) {
+    return map;
+  }
+  __bionic_name_mem(map, length, "libc_malloc");
+  return map;
 }
diff --git a/libc/bionic/dlmalloc.h b/libc/bionic/dlmalloc.h
index 71b3be8..e065687 100644
--- a/libc/bionic/dlmalloc.h
+++ b/libc/bionic/dlmalloc.h
@@ -17,6 +17,9 @@
 #ifndef LIBC_BIONIC_DLMALLOC_H_
 #define LIBC_BIONIC_DLMALLOC_H_
 
+#include <sys/cdefs.h>
+#include <stddef.h>
+
 /* Configure dlmalloc. */
 #define HAVE_GETPAGESIZE 1
 #define MALLOC_INSPECT_ALL 1
@@ -29,6 +32,12 @@
 #define USE_SPIN_LOCKS 0
 #define DEFAULT_MMAP_THRESHOLD (64U * 1024U)
 
+/* Export two symbols used by the VM. */
+__BEGIN_DECLS
+int dlmalloc_trim(size_t) __LIBC_ABI_PUBLIC__;
+void dlmalloc_inspect_all(void (*handler)(void*, void*, size_t, void*), void*) __LIBC_ABI_PUBLIC__;
+__END_DECLS
+
 /* Include the proper definitions. */
 #include "../upstream-dlmalloc/malloc.h"