Before [JDK-8347909](https://bugs.openjdk.org/browse/JDK-8347909) we had to remove the include lines in precompiled.hpp when precompiled headers were turned off. This was done by defining DONT_USE_PRECOMPILED_HEADER.

After [JDK-8347909](https://bugs.openjdk.org/browse/JDK-8347909) we simply don't include precompiled.hpp if precompiled headers are turn off and therefore we don't need to removed the include lines.

I propose that we get rid of DONT_USE_PRECOMPILED_HEADER.