More subsurface files and their modules

Almost all relevant subsurface files are now taken. This could be better
achieved by making a subsurface submodule. (Future)
For building these files, appropriate module addition for ndk-build and cross
compilation using ndk-standalone-toolchain is done.

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