argh, overlooked two extern crates

Author: nikomatsakis

src/librustc_incremental/Cargo.toml

@@ -14,3 +14,5 @@ rbml = { path = "../librbml" }
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 serialize = { path = "../libserialize" }
+log = { path = "../liblog" }
+syntax = { path = "../libsyntax" }