Fix missing MacOS dashes and function return issue

Dashes were missing from untar on MacOS.

Redirect fill_pyver errors to stderr, instead of returning them as the
result.

common_utils.sh

@@ -74,11 +74,11 @@ function untar {
     if [ -z "$in_fname" ];then echo "in_fname not defined"; exit 1; fi
     local extension=${in_fname##*.}
     case $extension in
-        tar) tar xf $in_fname ;;
-        gz|tgz) tar zxf $in_fname ;;
-        bz2) tar jxf $in_fname ;;
+        tar) tar -xf $in_fname ;;
+        gz|tgz) tar -zxf $in_fname ;;
+        bz2) tar -jxf $in_fname ;;
         zip) unzip $in_fname ;;
-        xz) unxz -c $in_fname | tar xf ;;
+        xz) unxz -c $in_fname | tar -xf ;;
         *) echo Did not recognize extension $extension; exit 1 ;;
     esac
 }

osx_utils.sh

@@ -90,7 +90,7 @@ function fill_pyver {
     elif [ $ver == "3.2" ]; then
         echo $LATEST_3p2
     else
-        echo "Can't fill version $ver"
+        echo "Can't fill version $ver" 1>&2
         exit 1
     fi
 }