RFR JDK-8022407 (round 2) sun/misc/CopyMemory.java fails with SIGSEGV in Unsafe_SetByte+0x35

[Lois Foltan]

Please review the updated webrev:
     open webrev at http://cr.openjdk.java.net/~hseigel/bug_jdk8022407.2/

Bug:
     bug link at https://bugs.openjdk.java.net/browse/JDK-8022407

Summary of fix:

     The JDK 8 build on MacOS, when built with the Xcode 4.6.2 clang++ 
compiler, exhibited a compiler
     optimization issue when prims/unsafe.cpp was compiled at the 
default -Os level. As a work around
     fix, knock the optimization level down down to -O1.

Tests: MacOS: built fastdebug & product images using clang++ (ran JTREG 
& vm.quick.testlist)
           built using llvm-g++ to verifyprims/unsafe.cpp remained 
compiled at -Os

Thank you, Lois