This reverts commit 7952d726e58c795babbbdefa6689dc30d9b7626b.

* Instead of vars in order dictated by client streamWriteVar.
* This allows for differential handling of different stream types.

* This way all header elements can later be accessed directly.

* This will later ease distinguishing both in the MPI window index.

* At least for more recent versions of distutils:sysconfig.

* Now autoconf 2.69 and automake 1.11.5 are used.