/usr/bin/libusb-config is in libusb-dev 2:0.1.12-23.3ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 | #!/bin/sh
prefix=/usr
exec_prefix=${prefix}
exec_prefix_set=no
usage()
{
	cat <<EOF
Usage: libusb-config [OPTIONS] [LIBRARIES]
Options:
	[--prefix[=DIR]]
	[--exec-prefix[=DIR]]
	[--version]
	[--libs]
	[--cflags]
EOF
	exit $1
}
if test $# -eq 0; then
	usage 1 1>&2
fi
while test $# -gt 0; do
  case "$1" in
  -*=*) optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'` ;;
  *) optarg= ;;
  esac
  case $1 in
    --prefix=*)
      prefix=$optarg
      if test $exec_prefix_set = no ; then
        exec_prefix=$optarg
      fi
      ;;
    --prefix)
      echo_prefix=yes
      ;;
    --exec-prefix=*)
      exec_prefix=$optarg
      exec_prefix_set=yes
      ;;
    --exec-prefix)
      echo_exec_prefix=yes
      ;;
    --version)
      echo 0.1.12
      exit 0
      ;;
    --cflags)
      if test "${prefix}/include" != /usr/include ; then
        includes="-I${prefix}/include"
      fi
      echo_cflags=yes
      ;;
    --libs)
      echo_libs=yes
      ;;
    *)
      usage 1 1>&2
      ;;
  esac
  shift
done
if test "$echo_prefix" = "yes"; then
	echo $prefix
fi
if test "$echo_exec_prefix" = "yes"; then
	echo $exec_prefix
fi
if test "$echo_cflags" = "yes"; then
	echo $includes
fi
if test "$echo_libs" = "yes"; then
	echo -L/usr/lib/x86_64-linux-gnu -lusb 
fi
 |