RFR: JDK-8202319: Fix compilation warnings in Solaris debug builds for DevStudio 12.6

[Gary Adams]

Getting the sources ready for the next Solaris developer studio toolchain.
Some additional warnings were found in the debug build.

    Issue: https://bugs.openjdk.java.net/browse/JDK-8202319
    Webrev: http://cr.openjdk.java.net/~gadams/8202319/webrev.00/

This update conditionally disables some new error checks, if the
new toolchain is used.

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