vchoi_fork

[svn-r16209] Purpose:
	Bug fix (#1357)

Description:
	Three filters have not assigned correct value to one value-result argument, "buf_size". N-bit, szip, and scale offset filter have had this problem.

	However, I don't think this problem has been making buffer overrun because those filters were informing the caller that the "buf", another value-result argument, is smaller than it actually is. If there was actual buffer overrun, I believe another problem exists although I don't know.

Tested:
	jam, smirom, linew

	Although all test were passed, I'm concerned about valgrind memcheck error. There can be another miscommunication between filter and the caller.