only memcpy into imsg->data if datalen is not zero Passing a NULL pointer to memcpy is UB no matter if len is 0 (commit by claudio@, backporting for kamid.)

Merge branch 'portable' Trying to maintain two branches was impossible at this stage for me alone, so I'll recognize my stupidity and merge the portable branch into the main one. The repository will build using autotools.

switch the -portable branch to autotools