quoted argument not unescaped

parser tells 
```bash
echo "-DEXPORT=__attribute__\\(\\(visibility\\(\\\"default\\\"\\)\\)\\)"
```
`arg[1]` is 
```bash
-DEXPORT=__attribute__\\(\\(visibility\\(\\\"default\\\"\\)\\)\\)
```
but it should be 
```bash
-DEXPORT=__attribute__\(\(visibility\(\"default\"\)\)\)
```

