RFR(S) 8216184: CDS/appCDS tests failed on Windows due to long path to a classlist file

[Calvin Cheung]

bug: https://bugs.openjdk.java.net/browse/JDK-8216184

webrev: http://cr.openjdk.java.net/~ccheung/8216184/webrev.00/

We are using fopen() to open a classlist file. fopen() can't handle long 
path name longer than MAX_PATH.

A fix is to use os::open() which is capable of handling long path name 
after the fix for JDK-8188122.

Testing: mach5 hs-tier{1,2,3}.

thanks,
Calvin