Generalize reconfigure script to work on more platforms.

* Hello *BSD.

scripts/reconfigure

-#! /bin/bash
+#! /usr/bin/env bash
 #
 # This script contains all the necessary steps to recreate the
 # autotools files to build PPM/YAXT.
@@ -38,25 +38,40 @@
 # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
+set -e
+
 case $(uname -s) in
   Darwin)
     libtoolize=glibtoolize
-    if which gsed >/dev/null 2>&1; then
-      sedi='gsed -i'
-    else
-      sedi="sed -i ''"
-    fi ;;
+    if [[ -z "${SED+set}" ]] && command -v gsed >/dev/null 2>&1; then
+      SED=gsed
+    fi
+    ;;
   *)
     libtoolize=libtoolize
-    sedi='sed -i' ;;
+    ;;
 esac
 
+SED=${SED-sed}
+if sed_version=$($SED --version) && [[ $sed_version = *GNU\ sed* ]]; then
+  sed_inplace_options=('-i')
+elif $SED -E </dev/null 2>/dev/null >/dev/null ; then
+  # assume modern FreeBSD sed
+  sed_inplace_options=('-i' '')
+else
+  printf '%s\n' 'Cannot find sed able to operate in place.' \
+    'Please provide full path to GNU or FreeBSD sed in SED environment variable.' \
+    >&2
+  exit 1
+fi
+
 $libtoolize --force --copy
+#todo: escape / in $libtoolize
 libtoolversion=$($libtoolize --version \
-                      | sed -e 's/^'$libtoolize' \(([^)]*) \)\{0,1\}\([0-9.]*\)/\2/;q')
+                      | ${SED} -e 's/^'"$libtoolize"' \(([^)]*) \)\{0,1\}\([0-9.]*\)/\2/;q')
 declare -a patches
 case "$libtoolversion" in
-  2.4.6)
+  (2.4.6)
     patches=(contrib/00nagfor-libtool-patch/nagfor-libtool-2.4.6.patch \
       contrib/01aix-deplib-rpath-patch/aix-deplib-libtool.patch \
       contrib/03ltmain-ld-groups-patch/ltmain-ld-groups-libtool-2.4.6.patch \
@@ -65,7 +80,7 @@ case "$libtoolversion" in
       contrib/06ltmain_nag_pthread-patch/ltmain_nag_pthread.patch \
       contrib/07ltmain-early-xcompile-patch/ltmain-early-xcompile-libtool-2.4.6.patch)
     ;;
-  2.4.2)
+  (2.4.2)
     patches=(contrib/00nagfor-libtool-patch/nagfor-libtool.patch \
       contrib/01aix-deplib-rpath-patch/aix-deplib-libtool.patch \
       contrib/02nagfor53-shared-patch/nagfor53-shared.patch \
@@ -80,7 +95,8 @@ for patch in "${patches[@]}"; do
   patch -p1 <$patch
 done
 autoreconf -i
-eval "find . -name Makefile.in -print0 | xargs -0 $sedi -e 's/[	 ][	 ]*\$//'"
+find . -name Makefile.in -exec $SED "${sed_inplace_options[@]}" \
+  -e 's/[	 ][	 ]*$//' \{\} +
 \rm -f config/ltmain.sh.orig m4/libtool.m4.orig
 wget -o /dev/null -O config/config.guess \
      'http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD'