RFR (S): Add a configure flag --<enable|disable>-tsan-launcher

[Man Cao]

Hi,

Can I have reviews for this:
https://cr.openjdk.java.net/~manc/tsan20190717/webrev.00/

Add a configure flag --<enable|disable>-tsan-launcher. This flag allows
more control on whether to link TSAN runtime with launcher. Default is
consistent with whether the JVM feature "tsan" is enabled.

Tested with 4 combinations of "--with-jvm-features=<tsan|-tsan>
--<enable|disable>-tsan-launcher".

-Man