dup3(3): Replace copyright notice.
dup3(3): Replace copyright notice.

Although I copied dup(2) to create dup3(3), I removed almost all the
non-boilerplate, so dup3(3) is copyright me.

Reported by:	bjk

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase