RFR(11u): 8222079: Don't use memset to initialize fields decode_env constructor in disassembler.cpp

[Roman Kennke]

Can I please get a review for the following 11u-backport:
http://cr.openjdk.java.net/~rkennke/JDK-8222079-jdk11u/webrev.00/
?

The original change is considerably different (and more complicated
because there are more constructors to take care of):
http://hg.openjdk.java.net/jdk/jdk/rev/963924f1c891

The change is useful in 11u because it removes a warning (that is
treated like an error by default) when compiling with GCC9+.

Testing: tier1 & tier2 without regressions

Is this ok for 11u?

Thanks,
Roman