RFR (S) 6424123: JVM crashes on failed 'strdup' call.

[Zhengyu Gu]

JVM should avoid C library's strdup() and use os::strdup() instead. 
os::strdup() handles OOM, so can avoid JVM crash.

Also, made limited scope of code cleanup, which makes memory ownership 
more explicit, so they can be claimed by object's destructors.

Bug: https://bugs.openjdk.java.net/browse/JDK-6424123
Webrev: http://cr.openjdk.java.net/~zgu/6424123/webrev.00/

Tests:
   - JPRT
   - vm.quick.testlist on Linux x64.

Thanks,

-Zhengyu