RFR: JDK-8055295 - existing GPIO tests not always close pins

[Stas Smirnov]

issue: JDK-8055295 <https://bugs.openjdk.java.net/browse/JDK-8055295>
webrev: 8055295 <http://cr.openjdk.java.net/%7Estsmirno/8055295/>

Hi All,

Need a review for an update.
These changes fixes insecure work with GPIO pins in existing GPIO tests 
replacing it using try-with-resources.

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Best regards,
Stas Smirnov

Stas Smirnov | Java Embedded
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