[lldb] Quick Fix: IRExecutionUnit check pointer before access it

[kusmour]

Summary

Move checking pointer code block before accessing the pointer
This caused lldb to crash when testing on Android

lldb/trunk/source/Expression/IRExecutionUnit.cpp

void IRExecutionUnit::GetRunnableInfo(Status &error, lldb::addr_t &func_addr,
   for (std::string &feature : m_cpu_features)
     mAttrs.push_back(feature);
 
   llvm::TargetMachine *target_machine =
       builder.selectTarget(triple, mArch, mCPU, mAttrs);
 
   m_execution_engine_up.reset(builder.create(target_machine));
 
-  m_strip_underscore =
-      (m_execution_engine_up->getDataLayout().getGlobalPrefix() == '_');
-
   if (!m_execution_engine_up) {
     error.SetErrorToGenericError();
     error.SetErrorStringWithFormat("Couldn't JIT the function: %s",
                                    error_string.c_str());
     return;
   }
 
+  m_strip_underscore =
+      (m_execution_engine_up->getDataLayout().getGlobalPrefix() == '_');
+
   class ObjectDumper : public llvm::ObjectCache {
   public:
     void notifyObjectCompiled(const llvm::Module *module,
                               llvm::MemoryBufferRef object) override {
       int fd = 0;
       llvm::SmallVector<char, 256> result_path;
       std::string object_name_model =
           "jit-object-" + module->getModuleIdentifier() + "-%%%.o";