Fix compilation error in clang

The compilation error was: 

```
duplicate symbol _clean in:
    build/temp.macosx-10.8-intel-2.7/facs/simple_check_1_ge.o
    build/temp.macosx-10.8-intel-2.7/facs/simple_remove.o
duplicate symbol _contam in:
    build/temp.macosx-10.8-intel-2.7/facs/simple_check_1_ge.o
    build/temp.macosx-10.8-intel-2.7/facs/simple_remove.o
duplicate symbol _clean2 in:
    build/temp.macosx-10.8-intel-2.7/facs/simple_check_1_ge.o
    build/temp.macosx-10.8-intel-2.7/facs/simple_remove.o
duplicate symbol _contam2 in:
    build/temp.macosx-10.8-intel-2.7/facs/simple_check_1_ge.o
    build/temp.macosx-10.8-intel-2.7/facs/simple_remove.o
ld: 4 duplicate symbols for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'clang' failed with exit status 1
make: *** [python] Error 1
```