Build numbers and milestones

[David Holmes]

I was baffled as to why my environment variables for setting the build 
number and milestone (which are traditionally set this way) were not 
getting picked up by the build.

Finally realized that the include of version.numbers was wiping them out:

JDK_BUILD_NUMBER=
MILESTONE=internal

I've deleted the above lines locally. I think they should either be 
deleted formally or else only set if not already set. You don't expect 
either of these values to be written into version file in the repo 
(unless you are expecting them to be updated for every build as the 
hotspot version info is?).

David