* infcmd.c (set_environment_command): Make set env FOO x=y work.

* infcmd.c (set_environment_command):  Make set env FOO x=y work.
Fix from maj@lucid.com.
* remote-udi.c (udi_open):  Reset vars so that user can re-run
programs without leaving GDB.
* (many routines):  Slightly improve error handling.
* (download):  Zero out BSS by longs instead of bytes to avoid
timeouts in real hardware.
* 29k-share/udi/udip2soc.c (UDIDisconnect, UDIKill):  Indicate
that connection is no longer in use after shutdown() of socket.
This keeps GDB from dying of a SIGPIPE when you issue multiple
`target udi' commands.