Improve 'flags' and the gcc toolset.
* gcc.jam: Extend the 'toolset' feature with gcc here.
Use flags for linking too and eliminate 'link-options'
rule. Remove empty compile/archive/link/link-dll rules.
* toolset.jam (flags): Document somehow.
(set-target-variables): Call 'actualize' on values
of dependency features.
[SVN r16440]
Vladimir Prus