new IncrementalBuild to support building only modules provided as arg
new IncrementalBuild to support building only modules provided as arg

this is more or less restoring of the original implementation
@jacobgreenleaf removed in PR #563. We didn't have use case for this
code to exists but our build times are getting longer and we need to way
to reduce the build time.

uber/zanzibar,uber/zanzibar,uber/zanzibar