build: remove C99 designated initializers for Microsoft's compiler

- Microsoft's compiler doesn't support C99 designated initializers.
  Hopefully this we be added in the future, but for now we can
  comment the '.fieldname =' to achieve the same initialization,
  as long as all the elements are initialized in the fixed order
  that they were declared.

Change-Id: I38af2eb66d583ef8f280ff8b4c7065c7d8229c02
Tuleap: #790