RFR: 8241371: Refactor and consolidate package_from_name

[Claes Redestad]

Correct webrev: http://cr.openjdk.java.net/~redestad/8241371/open.00/
Bug:            https://bugs.openjdk.java.net/browse/JDK-8241371

On 2020-03-22 17:15, Claes Redestad wrote:
> Hi,
> 
> JDK-8153858 partially consolidated the logic shared between
> InstanceKlass::package_from_name and ClassLoader::package_from_name.
> Unfortunately it also caused an undetected regression in some paths due
> need to copy from Symbol -> resource arrays and back again.
> 
> By refactoring package_from_name into a single implementation which
> operates on a Symbol* rather than a char* we can both simplify a bit
> and regain some lost performance:
> 
> Testing: tier1-5, verified a ~0.5% improvement on startup
> 
> Thanks!
> 
> /Claes