RFR: 8200072: Remove un-needed qualified export from java.base to java.desktop

[Phil Race]

Bug: https://bugs.openjdk.java.net/browse/JDK-8200072
webrev: http://cr.openjdk.java.net/~prr/8200072/

jdk.internal.math is exported to java.desktop but it has never been needed,
except briefly, in the jake forest during JDK 9 development.
History is in the bug.

-phil.