Fix includes and DBus headers to build on Android.

This patch include a set of small changes to includes and names in
order to be compatible with the Android build system.

First, the DBus .xml file needs to be renamed to .dbus-xml and the
output directory must match the soruce directory, since the headers are
generated with automatic Makefile rules.

Some headers required by bionic were missing, such as endian.h and
xattr.h. In the xattr.h case, we include the header from the glibc
(or bionic) instead of libattr, since libattr is not available in
AOSP in the first place, and we are not linking against it Chrome OS,
so we shold include the right headers.

Bug: 23084776
TEST=`FEATURES=test emerge-link update_engine` works; `mma` in AOSP doesn't have these errors anymore (but still doesn't build).

Change-Id: Ifeedfe9d894ca78baa03940ac55563cfcd464e76
diff --git a/utils.cc b/utils.cc
index a50e56a..2baa087 100644
--- a/utils.cc
+++ b/utils.cc
@@ -20,6 +20,7 @@
 
 #include <dirent.h>
 #include <elf.h>
+#include <endian.h>
 #include <errno.h>
 #include <ext2fs/ext2fs.h>
 #include <fcntl.h>