Removed unused variables

Author: Vladimir Kempik

src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp

@@ -272,11 +272,6 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
           stub = SharedRuntime::handle_unsafe_access(thread, next_pc);
         }
       } else if (sig == SIGILL && nativeInstruction_at(pc)->is_stop()) {
-        // Pull a pointer to the error message out of the instruction
-        // stream.
-        const uint64_t *detail_msg_ptr
-          = (uint64_t*)(pc + NativeInstruction::instruction_size);
-        const char *detail_msg = (const char *)*detail_msg_ptr;
         const char *msg = "stop";
         if (TraceTraps) {
           tty->print_cr("trap: %s: (SIGILL)", msg);