S RFR JDK-8024050: Incorrect optimization level and comment specified for unsafe.cpp

[Lois Foltan]

Please review the following fix:
     open webrev at http://cr.openjdk.java.net/~hseigel/bug_jdk8024050/

Bug: bug link at https://bugs.openjdk.java.net/browse/JDK-8024050

Summary of fix:

     The original sources used for the JDK-8022407 webrev sponsorship 
contained an incorrect optimization
     level specification for unsafe.cpp that was fixed on the MacOS 
machine prior to testing.  Unfortunately,
     this incorrect specification of -01 instead of -O1 was committed.  
In addition, corrected the comment for
     the Clang optimization level skew issue between PCH Files and files 
of different optimization levels.

Tests:
     MacOS: built fastdebug & product images using clang++ and llvm-g++ 
Ran original JDK-8022407 test case.
                   JTREG testing in progress.

Thank you,
Lois