fix stdout & stderr redirection

[lager1]

The redirection in gdb command is most likely mistyped. The was it is written it passes an argument 2 to the gdb and it actually produces a file 1.

gdb ... 2&>1 >/dev/null

The author most likely wanted to write the code below which redirects the stderr to stdout and then both to /dev/null:

gdb ... 2>&1 >/dev/null

This PR fixes that.