* src/threads/posix/thread-posix.cpp: Implemented thread suspension mechanism.

* src/threads/posix/thread-posix.cpp: Implemented thread suspension mechanism.
* src/threads/posix/thread-posix.hpp: Likewise.
* src/threads/threadlist.cpp (ThreadList::dump_threads): Use above mechanism.
* src/native/vm/openjdk/jvm.cpp (JVM_SuspendThread, JVM_ResumeThread): Likewise.

* src/vm/signal.cpp (signal_handler_sigusr1): Added generic suspension handler.
* src/vm/signallocal.hpp (md_signal_handler_sigusr1): Removed prototype.
* src/vm/jit/alpha/linux/md-os.c: Removed implementation of above function.
* src/vm/jit/arm/linux/md-os.c: Likewise.
* src/vm/jit/i386/freebsd/md-os.c: Likewise.
* src/vm/jit/i386/linux/md-os.c: Likewise.
* src/vm/jit/i386/solaris/md-os.c: Likewise.
* src/vm/jit/m68k/linux/md-os.c: Likewise.
* src/vm/jit/powerpc/linux/md-os.c: Likewise.
* src/vm/jit/x86_64/linux/md-os.c: Likewise.
* src/vm/jit/x86_64/solaris/md-os.c: Likewise.