don't throw UnknownHostException from InetAddress.getByName("0.0.0.0")

0.0.0.0 means any local interface, which is commonly used by servers
which wish to listen on all interfaces.
throw UnknownHostException if host is not found in InetAddress.getByName
fix build regression on platforms with no native 64-bit CAS

Unsafe.compareAndSwapLong was moved from classpath-openjdk.cpp to
builtin.cpp, but the fieldForOffset helper function was not, which
only caused problems when I tried to build for ARM.  This commit moves
said helper function, along with Unsafe.getVolatileLong, which also
uses it.
fix iOS 7 build using latest Xcode

It looks like the iOS 7 SDK doesn't have GCC anymore, so we need to
use clang instead.  Also, thread_act.h and thread_status.h have moved,
so I updated arm.h accordingly.  That might break the build for older
SDKs, but I don't have one available at the moment.  If it does break,
I'll fix it.
fix header include order build regression
Merge pull request #139 from dicej/master

don't throw UnknownHostException from InetAddress.getByName("0.0.0.0")