* src/vm/vm.cpp (VM::abort): Removed.

* src/vm/vm.cpp (VM::abort): Removed.
(VM::abort_errnum, VM::abort_errno): Likewise.
* src/vm/vm.hpp (VM): Likewise.
* src/vm/os.cpp (os::abort): New function.
(os::abort_errnum, os::abort_errno): Likewise.
* src/vm/os.hpp (os): Likewise.
* src/mm/gc-boehm.cpp,
src/threads/posix/condition-posix.hpp,
src/threads/posix/mutex-posix.hpp,
src/threads/posix/thread-posix.hpp,
src/vm/assertion.cpp,
src/vm/exceptions.cpp,
src/vm/jit/optimizing/bytecode_escape.c,
src/vm/primitive.cpp,
src/vm/properties.cpp,
src/vm/string.cpp,
src/vm/suck.cpp: Related changes.