Only search for the gpt tool if we need it.

src/scripts/emit_gpt_scripts.sh

 #!/bin/bash
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # Emit scripts to pack and unpack the partitions from a GPT disk image.
 
 # Load common constants.  This should be the first executable line.
 # The path to common.sh should be relative to your script's location.
 . "$(dirname "$0")/common.sh"
 . "$(dirname "$0")/chromeos-common.sh"
 
 set -e
 
 # Usage
 IMAGE=${1:-}
 DIR=${2:-}
 if [[ -z "$IMAGE" || -z "$DIR" ]]; then
   echo "Usage: $0 GPT_DEVICE DIRECTORY" 1>&2
   exit 1
 fi
 
 PACK="${DIR}/pack_partitions.sh"
 UNPACK="${DIR}/unpack_partitions.sh"
 
+locate_gpt
+
 TMP=$(mktemp)
 sudo $GPT -r show -l "$IMAGE" > $TMP
 
 HEADER='#!/bin/sh -eu
 # File generated by emit_gpt_scripts.sh. Do not edit.
 TARGET=${1:-}
 if [[ -z "$TARGET" ]]; then
   echo "Usage: $0 DEVICE" 1>&2
   exit 1
 fi
@@ skipping 12 matching lines @@
     echo "dd if=$loc of=$file bs=512 skip=$start count=$size" \
       >> "$UNPACK"
     echo \
       "dd if=$file of=$loc bs=512 seek=$start count=$size conv=notrunc" \
       >> "$PACK"
   done
 
 chmod +x "$PACK" "$UNPACK"
 
 rm $TMP