gbuild: ExtensionPackage: fix incremental builds wrt. Package here too
gbuild: ExtensionPackage: fix incremental builds wrt. Package here too

Change-Id: If37bd98faa6ec043ceb73a0cdfb8dddef7a6359e

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core