message: added comment in eosio_build.sh to explain how to use EOS_BUILD_TYPE
diff: COMPILE_EOS=1
  COMPILE_CONTRACTS=1
  -# CMAKE_BUILD_TYPE=RelWithDebInfo
  +# export EOS_BUILD_TYPE=[Debug|Release|RelWithDebInfo|MinSizeRel] to enable
  CMAKE_BUILD_TYPE=Release
  if [ ! -z $EOS_BUILD_TYPE ]; then
  CMAKE_BUILD_TYPE=$EOS_BUILD_TYPE
  