RFR(S): 8241556: Memory leak if -XX:CompileCommand is set

[Man Cao]

Hi all,

Could I have reviews for this fix for a memory leak? This memory leak is
pretty significant in production, and it took us weeks to identify the root
cause.
Webrev: https://cr.openjdk.java.net/~manc/8241556/webrev.00/
Bug: https://bugs.openjdk.java.net/browse/JDK-8241556

A more elegant fix would be to use automatic allocation/deallocation on the
char*. Unfortunately std::string and std:unique_ptr are both unavailable in
HotSpot.

-Man