remove installed file if openrtm_aist_FOUND is not found, and do not con...

...figure when system runs make again

current openrtm_asit package fail to compile on following situation. this PR wil fixes.
this situation is similar to https://github.com/start-jsk/openhrp3/issues/44
```
catkin_make
rm -fr build/CMakeCache.txt
catkin_mail
```