S. 115JB : Book profit-While computing book profit under section 115JB, entire amount of profits eligible under section 80HHC was to be excluded from book profit and not 80 per cent thereof-Sales tax incentive/remission received by assessee-company under State incentive scheme linked to fixed capital investment for expansion in a backward area, being capital in nature, was to be excluded from computation of book profit under section 115JB and fell outside ambit of income under section 2(24) [S.2(24), 80HHC, 260A]