RFR: 8079093: Remove FakeRttiSupport workaround for gcc -Wtypes-limit

[Kim Barrett]

Please review this removal of a workaround to avoid spurious compiler
warnings when building on MacOSX.

With the move to a newer minimum compiler version for MacOSX, the
workaround is no longer needed.

CR:
https://bugs.openjdk.java.net/browse/JDK-8079093

Webrev:
http://cr.openjdk.java.net/~kbarrett/8079093/webrev/

Testing:
JPRT