Fix crash issue

Fix crash issue

This patch is for a below crash issue.

#3  0xb6d503ce in __GI_abort () at abort.c:79
#4  0xb706dc1c in __gnu_cxx::__verbose_terminate_handler ()
    at ../../../../libstdc++-v3/libsupc++/vterminate.cc:95
#5  0xb707c336 in __cxxabiv1::__terminate (
    handler=0xb707e820 <__gnu_cxx::__verbose_terminate_handler()>)
    at ../../../../libstdc++-v3/libsupc++/eh_terminate.cc:47
#6  0xb707c39f in std::terminate () at ../../../../libstdc++-v3/libsupc++/eh_terminate.cc:57
#7  0x800b2cba in std::thread::~thread (this=0x810b5a9c, __in_chrg=<optimized out>)
    at /usr/lib/gcc/i586-tizen-linux-gnu/9.2.0/include/c++/thread:139
#8  launchpad::Worker::~Worker (this=0x810b5a80, __in_chrg=<optimized out>)
    at /usr/src/debug/launchpad-0.36.3-1.i386/src/launchpad-process-pool/worker.cc:46
#9  0x800b2ce2 in launchpad::Worker::~Worker (this=0x810b5a80, __in_chrg=<optimized out>)
    at /usr/src/debug/launchpad-0.36.3-1.i386/src/launchpad-process-pool/worker.cc:46
#10 0x8009978c in std::default_delete<launchpad::Worker>::operator() (
    this=0x800ccb18 <launchpad::SignalManager::GetInst()::inst+280>, __ptr=<optimized out>)
    at /usr/lib/gcc/i586-tizen-linux-gnu/9.2.0/include/c++/bits/unique_ptr.h:75
#11 std::unique_ptr<launchpad::Worker, std::default_delete<launchpad::Worker> >::reset (
    __p=<optimized out>, this=0x800ccb18 <launchpad::SignalManager::GetInst()::inst+280>)
    at /usr/lib/gcc/i586-tizen-linux-gnu/9.2.0/include/c++/bits/unique_ptr.h:394
#12 launchpad::SignalManager::Dispose (
    this=this@entry=0x800cca00 <launchpad::SignalManager::GetInst()::inst>)
    at /usr/src/debug/launchpad-0.36.3-1.i386/src/launchpad-process-pool/signal_manager.cc:121
#13 0x8009983f in launchpad::SignalManager::Dispose (
    this=0x800cca00 <launchpad::SignalManager::GetInst()::inst>)
    at /usr/src/debug/launchpad-0.36.3-1.i386/src/launchpad-process-pool/signal_manager.cc:171
#14 launchpad::SignalManager::~SignalManager (
    this=0x800cca00 <launchpad::SignalManager::GetInst()::inst>, __in_chrg=<optimized out>)
    at /usr/src/debug/launchpad-0.36.3-1.i386/src/launchpad-process-pool/signal_manager.cc:171
#15 0xb6d6bfff in __run_exit_handlers (status=status@entry=-1, listp=0xb6f0339c <__exit_funcs>,
    run_list_atexit=run_list_atexit@entry=true, run_dtors=run_dtors@entry=true) at exit.c:108
#16 0xb6d6c1d5 in __GI_exit (status=-1) at exit.c:139
#17 0x80096948 in launchpad::ProcessPool::OnExecution (this=<optimized out>)
    at /usr/src/debug/launchpad-0.36.3-1.i386/src/launchpad-process-pool/process_pool.cc:118
#18 0x80071b03 in launchpad::Executor::Execute (this=this@entry=0x810b8044,
    priority=priority@entry=0)
    at /usr/src/debug/launchpad-0.36.3-1.i386/src/launchpad-process-pool/executor.cc:50
#19 0x80096b09 in launchpad::ProcessPool::PrepareProcess (this=0x810b8040)

Change-Id: I96ff11d3fb0fc6d368d531e4ecc38bf10135bc84
Signed-off-by: Changgyu Choi <changyu.choi@samsung.com>