fix error in linux makefile for some shells

platform_tools/barelinux/bin/barelinux_make

 #!/bin/sh
 
 # Copyright 2014 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 usage() {
     cat >&2 <<EOF
 barelinux_make - this script builds a version of skia that does not
@@ skipping 16 matching lines @@
     skia_gpu=0 skia_arch_type=arm skia_arch_width=64 \\
     armv7=1 armv8=1 arm_neon=0 arm_thumb=0
 EOF
     return 1
 }
 
 # BUILD_TYPE should be one of:
 #  Coverage, Debug, Release, or Release_Developer
 BUILD_TYPE='Debug'
 
-unset OPTIND
 while getopts ":c:x:o:t:h" opt ; do
     case $opt in
         c)  export CC="$OPTARG" ;;
         x)  export CXX="$OPTARG" ;;
         o)  export SKIA_OUT="$OPTARG";;
         t)  BUILD_TYPE="$OPTARG";;
         h)  usage || exit;;
         ?)  echo "unknown option '$OPTARG'" >&2;
             usage || exit;;
     esac
@@ skipping 39 matching lines @@
     skia_poppler_enabled=0 \
     skia_skip_gui=1 \
     "
 
 try "${SKIA_SRC_DIR}/gyp_skia" || exit
 
 try test -d "${SKIA_OUT}/${BUILD_TYPE}" || exit
 
 try ninja -C "${SKIA_OUT}/${BUILD_TYPE}" || exit