Fix a bug that joined us at the last minute, when an efficient
alloca() call got swapped out for a more portable malloc().

Also log one error, to give a clue in case it appears "in the wild".


git-svn-id: svn://svn.berlios.de/openocd/trunk@1907 b42882b7-edfa-0310-969c-e2dbd0fdcd60