RFR: JDK-8231594: Configure fails on some Linux systems

[Tim Bell]

Erik:

> In my recent change JDK-8206125, I introduced a bash conditional that 
> checks if a string starts with ~. That check seems to fail on some Linux 
> systems unless the ~ is quoted.

That's a very dark corner for the shell to be in...

> Bug: https://bugs.openjdk.java.net/browse/JDK-8231594
> 
> Webrev: http://cr.openjdk.java.net/~erikj/8231594/webrev.01

Looks good.

Tim