I was looking through cleaning up mi/ global state, and noticed
the global mi_error_message used to output ^error,msg=""
messages.

I then noticed that the errors output by the mi/ module are
also duplicated to stderr.

>./gdb -i=mi
~"GNU gdb 6.8.50.20080323-cvs\n"
~"Copyright (C) 2008 Free Software Foundation, Inc.\n"
~"License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>\n"
~"This is free software: you are free to change and redistribute it.\n"
~"There is NO WARRANTY, to the extent permitted by law.  Type \"show 
copying\"\n"
~"and \"show warranty\" for details.\n"
~"This GDB was configured as \"x86_64-unknown-linux-gnu\".\n"
~"Setting up the environment for debugging gdb.\n"
&"/home/pedro/gdb/head/build/gdb/.gdbinit:5: Error in sourced command file:\n"
&"No symbol table is loaded.  Use the \"file\" command.\n"
(gdb)
-exec-continue
^running
(gdb)
&"The program is not being run.\n"
^error,msg="The program is not being run."
(gdb)


Notice the duplication:
&"The program is not being run.\n"
^error,msg="The program is not being run."

I can't find a valid reason for that.
In fact having them display in gdb's output window in a
frontend doesn't help anyone, especially, since ^error is supposed
to be the error output channel.  Furthermore, there are a couple
of cases that weren't using the mechanism correctly, as they
were already calling error.

The attached patch fixes it, and fixes the testsuite to not
expect this duplication.

-- 
Pedro Alves