Unnecessary calls in BlockBuffer::getFreeBlock()

[SaintNerevar]

Block type is already set when setting the header using setHeader(). There is no need to call setBlockType again.
setHeader() also calls getBufferPtr() which in turn calls getBlock() which calls getFreeBuffer() (everytime since the block number corresponds to an unallocated block) which makes calling getFreeBuffer() in getFreeBlock() unnecessary.

[gokulsreekumar]

• setHeader() and setBlockType() is being modified for issue #22