Make bionic_malloc.h a platform header.

Instead of having platform directories directly include the
private header, create a platform header directory and export it.

Bug: 130763340

Test: Builds.
Change-Id: Ie0f092b3fe077a3de8b90266c0b28bfbc20d0dfa
Merged-In: Ie0f092b3fe077a3de8b90266c0b28bfbc20d0dfa
(cherry picked from commit 8f582ef2f8a77d953d0e9f33387f592d20f852e2)
diff --git a/libc/malloc_hooks/Android.bp b/libc/malloc_hooks/Android.bp
index d119f89..a0f8102 100644
--- a/libc/malloc_hooks/Android.bp
+++ b/libc/malloc_hooks/Android.bp
@@ -49,7 +49,13 @@
     shared_libs: ["libbase"],
 
     local_include_dirs: ["tests"],
-    include_dirs: ["bionic/libc", "bionic"],
+    include_dirs: [
+        "bionic/libc",
+        "bionic"
+    ],
+    header_libs: [
+        "bionic_libc_platform_headers",
+    ],
 
     cflags: [
         "-Wall",