corrected previous patch removing  "if (signal)", which should acually be "if (signum)"


ndb/src/common/debugger/EventLogger.cpp:
  corrected previous patch removing  "if (signal)", which should acually be "if (signum)"
ndb/src/kernel/blocks/dbtc/Dbtc.hpp:
  remove unused errorcode
ndb/src/ndbapi/ndberror.c:
  remove unused errorcode