introduce separate <link-runtime> feature.
Allow to use the 'lib' rule to declare
libraries that should be searched for.
* builtin.jam: Remove 'shared' features. Introduce
'link' and 'link-runtime'.
(searched-lib-target): New class
(searched-lib-generator): New generator.
(lib-action): New class, derived from 'action'.
Handles instances of 'searched-lib-target' in sources.
Also, moves all libraries from sources to property value,
so that we can repeat them twice in command line.
(lib-generator): Generator which uses 'lib-action'.
* generators.jam: Allow empty list of sources everywhere.
* virtual-target.jam (file-target): Split into
'abstract-file-target' and 'file-target'.
(abstra
(action.actualize-sources): New rule. Allows to
handle the fact that some sources are special,
and should not become $(>) in action body.
[SVN r16573]
