Enhance error msg and remove superfluous semicolon

[michaelortmann]

Found by: michaelortmann
Patch by: michaelortmann
Fixes:

One-line summary:
Enhance error msg and remove superfluous semicolon

Additional description (if needed):

Test cases demonstrating functionality (if applicable):
.tcl listen 1.2.3.4 2345 users
Before:

.tcl listen 1.2.3.4 2345 users
Tcl error: Couldn't listen on port '2345' on the given address: Cannot assign requested address. Please check that the port is not already in use

After:

Tcl error: Couldn't listen on port 2345 on the given address '1.2.3.4': Cannot assign requested address. Please check that the port is not already in use