[CMake] Sema depends on Serialization these days. (#10968)

Specifically, it uses SerializedASTFile::getLanguageVersionBuiltWith
to improve diagnostics. Not having this has led to failures on Linux,
where linking order matters.

Author: jrose-apple

lib/Sema/CMakeLists.txt

@@ -57,6 +57,7 @@ add_swift_library(swiftSema STATIC
   LINK_LIBRARIES
     swiftParse
     swiftAST
+    swiftSerialization
   ${EXTRA_TYPECHECKER_FLAGS}
 )