android: Add btmgmt to debug builds
android: Add l2ping to debug builds
android: Refactor paths in Android.mk

Using source paths relative to android/ directory created mess in
Android's obj directory since object files are created also relative
to bluetoothd_intermediates (thus can be created outside it).

To avoid this we set LOCAL_PATH to absolute path (in terms of Android
build root) of directory in which bluez/ is located and change and
update source paths accordingly.

This also allows us to build in future glib and sbc easily using
Android.mk in BlueZ.
tools/l2cap-tester: Fix indentation
android/pan: Fix wrong freeing dev

It does make sense free() dev after it is used. g_free() is not needed
here since it will be already executed in bt_pan_notify_conn_state().
btproxy: Fix resource leak

Close file descriptors if setup_proxy fails.
unit/sdp: Remove extra zero table entry

It is enough to have one zero table entry at the end of the table.
unit/avdtp: Remove extra zero table entry

Remove not needed table entry copied, probably, from unit/sdp
tools: Close file descriptors in the calling function
core: Remove __TEXTFILE_H header inclusion protection
android/ipc: trivial: Remove empty line
android/pan: Fix possible NULL dereference

It is better to return here since dev is not allocated and assigned NULL
value.
android/pan: Remove not needed intialization to NULL
[travis-ci] Add configuration file
android: Fix GNU old-style struct field designator

This gives a warning on clang, that turns into an error due to -Werror.