[PATCH] Allow configure to pass with non-bash shells

Hi all,

The attached patch (by Ryan Hill) fixes two minor issues that cause problems when using a non-bash shell as /bin/sh (or when forcing configure through such a shell). It replaces them with more portable equivalents. This is unchanged between 0.143 and master.

The errors dash reported were:

./configure: 5467: Bad substitution

and after fixing that:

./configure: 5498: Syntax error: "(" unexpected

both of which cause the script to abort.

Is this something you can include in the next release?