Try to guess sed options depending on system

moo/mooutils/moo-intltool-merge

@@ -1,5 +1,20 @@
 #! /bin/sh
 
+if [ ! -z "`which gsed >/dev/null`" ]; then
+  sed=gsed
+  ext_opt=-r
+else
+  sed=sed
+  case `uname` in
+    Darwin|*BSD)
+      ext_opt=-E
+      ;;
+    *)
+      ext_opt=-r
+      ;;
+  esac
+fi
+
 if [ $# != 2 ]; then
   echo "usage: $0 src_file dst_file" > /dev/stderr
   exit 1
@@ -9,12 +24,12 @@ src="$1"
 dst="$2"
 
 do_xml() {
-  sed -e 's@<_@<@g' -e 's@</_@</@g' "$src" > "$dst.tmp" || exit 1
+  $sed -e 's@<_@<@g' -e 's@</_@</@g' "$src" > "$dst.tmp" || exit 1
   mv "$dst.tmp" "$dst" || exit1
 }
 
 do_desktop() {
-  sed -r -e 's@^_(\w+)=@\1=@g' "$src" > "$dst.tmp" || exit 1
+  $sed $ext_opt -e 's@^_(\w+)=@\1=@g' "$src" > "$dst.tmp" || exit 1
   mv "$dst.tmp" "$dst" || exit1
 }