Upgrade to dlmalloc 2.8.5.

Move dlmalloc code to upstream-dlmalloc to make pulling upstream changes
easier.
Declare pvalloc and malloc_usable_size routines present in malloc.h but with
missing implementations. Remove other functions from malloc.h that have
no implementation nor use in Android.

Change-Id: Ia6472ec6cbebc9ad1ef99f4669de9d33fcc2efb4
diff --git a/libc/upstream-dlmalloc/README.txt b/libc/upstream-dlmalloc/README.txt
new file mode 100644
index 0000000..bd5f3c6
--- /dev/null
+++ b/libc/upstream-dlmalloc/README.txt
@@ -0,0 +1,10 @@
+This directory contains malloc/free routines implemented by Doug Lea
+(aka dlmalloc). You should not edit these files directly. Make fixes
+upstream and then pull down the new version of the file.
+
+This code is imported from: ftp://g.oswego.edu/pub/misc/
+It is currently version 2.8.5.
+
+Currently there are very minor modifications that are signified with:
+BEGIN android-changed: change description
+END android-changed