build/jam/OptionalPackageDependencies and include it earlier (before the
Jamfiles).
* Introduced build/jam/OptionalBuildFeatures which is supposed to do the setup
for optional build features that need it.
* Renamed USE_SSL to HAIKU_BUILD_FEATURE_SSL and made it more intelligent.
The OpenSSL optional package is downloaded and unzipped automatically when
enabled. Switching between enabled/disabled HAIKU_BUILD_FEATURE_SSL is
handled gracefully -- the concerned components are built in separate
subdirectories. Adding the OpenSSL optional package to the image also enables
HAIKU_BUILD_FEATURE_SSL.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30021 a95241bf-73f2-0310-859d-f6bbb57e9c96
