hg: jdk9/sandbox/jdk: 8160370: System.getProperty("os.version") returns "Unknown" on Mac

[chris.hegarty at oracle.com]

Changeset: b72c37787a5e
Author:    bchristi
Date:      2016-06-30 10:13 -0700
URL:       http://hg.openjdk.java.net/jdk9/sandbox/jdk/rev/b72c37787a5e

8160370: System.getProperty("os.version") returns "Unknown" on Mac
Summary: Read SystemVersion.plist on pre-10.9 Mac OS
Reviewed-by: bpb, ddehaven, gziemski, rriggs

! src/java.base/macosx/native/libjava/java_props_macosx.c