MFC r268857: ttyname(3): Fix EBADF/ENOTTY error descriptions.
MFC r268857: ttyname(3): Fix EBADF/ENOTTY error descriptions.

Also, make sure to document the return values and errors for all three
functions in the man page.

PR:		191931

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