help.c as replacement of qthelper.c

qthelper contains some important helper codes. These were earlier using Qt
libraries. But help.c does not use any Qt and attempts to do all the work using
only C. This is a trial code and would most definitely contain huge errors. It
needs thorough testing soon.
For exif manipulation, we are using libexif. Hence it has been added to build.sh
and jni/Android.mk.

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