Add an option to provide extra environment variables for build
Binary package hint: xdeb
Xdeb uses debuild to make a build. As a result it is impossible to cross build kernels with xdeb due to lack of CROSS_COMPILE variable during kernel build.
Solution would be adding option which would take list of environment variables which will be provided for debuild. Other option could be "--debuild-opts" which will take a list of extra arguments for debuild calls.