RFR: JDK-8166937: [Solaris] Missing libjvm_db.so and libjvm_dtrace.so from JDK 9 b138

[Erik Joelsson]

On Solaris, we used to always add /usr/sbin to the global PATH early in 
configure since some tools we need are found there. In JDK-8165161 that 
was removed. This had the consequence that configure no longer found 
dtrace unless the user had /usr/sbin in the PATH. When configure doesn't 
find dtrace, it will by default simply disable dtrace support in the 
hotspot build. This patch fixes two things.

* Since Oracle builds on Solaris expect dtrace to be enabled, I added 
--enable-dtrace to the Jib configuration for Solaris profiles. That way 
we get an early failure if dtrace is missing.

* I added /usr/sbin to the path specifically when searching for dtrace 
since that is a known location for the tool that is not always present 
in the user path.

Bug: https://bugs.openjdk.java.net/browse/JDK-8166937

Webrev: http://cr.openjdk.java.net/~erikj/8166937/webrev.01/

/Erik