[foreign] rename package nicl to foreign

[Maurizio Cimadamore]

Hi,
as part of the code restructuring, here's a webrev which updates the 
packages names to the new form:

nicl -> foreign
nicl.types -> foreign.memory
nicl.metadata -> foreign.annotations
nicl.layout -> foreign.layout

I've also did similar renaming in the test folder, and I've changed the 
test group form jdk_nicl to jdk_foreign.

Most of the webrev is straightforward and IDE generated - however there 
were changes that I had to do manually, in cpp files, makefiles and 
other configuration files, as well as in some jextract hard coded constants.

Webrev:

http://cr.openjdk.java.net/~mcimadamore/panama/foreign_rename/

Cheers
Maurizio