Modify unaligned output of snoop's usage() function

Use space instead of tab, and the output is like this:

Usage:  snoop
    [ -a ]                       # Listen to packets on audio
    [ -d link ]                  # Listen on named link
    [ -s snaplen ]               # Truncate packets
    [ -I IP interface ]          # Listen on named IP interface
    [ -c count ]                 # Quit after count packets
    [ -P ]                       # Turn OFF promiscuous mode
    [ -D ]                       # Report dropped packets
    [ -S ]                       # Report packet size
    [ -i file ]                  # Read previously captured packets
    [ -o file ]                  # Capture packets in file
    [ -n file ]                  # Load addr-to-name table from file
    [ -N ]                       # Create addr-to-name table
    [ -t  r|a|d ]                # Time: Relative, Absolute or Delta
    [ -v ]                       # Verbose packet display
    [ -V ]                       # Show all summary lines
    [ -p first[,last] ]          # Select packet(s) to display
    [ -x offset[,length] ]       # Hex dump from offset for length
    [ -C ]                       # Print packet filter code
    [ -q ]                       # Suppress printing packet count
    [ -r ]                       # Do not resolve address to name

    [ filter expression ]

Example:
    snoop -o saved  host fred

    snoop -i saved -tr -v -p19