Update submodules

Libftdi, libdivecomputer and libusb submodules are updated.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>
Qmake build for subsurface.

Build subsurface using qmake build rather than Android ndk build. This provides
greater uniformity to the subsurface builds all over. For building Qt for anroid
is necessary and is referenced in the build. Changes are made in file descriptor
setting taking care to setup a void *devparam rather than int fd. The subsurface
code is modified accordingly but not yet committed.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>
Don't throw null filename error when unticked

Fixes #10

If log checkbox is unticked. The application threw null logfilename error. Fixed
it by checking boolean log value first.
Minute change in Android.mk to provide proper path to libsubsurface_jni.a file.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>