bugfix: redirecting the const base per event instead of the const base per block...

bugfix: redirecting the const base per event instead of the const base per block to the GetOutputSize method
Originally only one constBase parameter was foreseen in the interface which should give the number of bytes required in
the output buffer independent of the inout size. This has been changed to two parameters in r27692, one parameter
per event and one per block. The AliHLTComponent interface, though had not been changed and the wrong parameter
was passed onto the interface. This created trouble when having many input blocks.