Intel fftw mpi update for MKL >= 11.1

We have fftw2 and fftw3. These without mpi at all. In the case of fftw2 we have single (4 bytes) and double (8 bytes) precision libraries, up to now, we only build double precision ones. The fftw3 library contains both single and double precision functions. (there is no lp64 and ilp64 versions, se details in the next)
We have also the mpi version of those libraries, called fftw2_cdft and fftw3_cdft. with fftw2_cdft, we have single and double precision and 4 (lp64) and 8 (ilp64) bytes indexes. with fftw3_cdft, the single and double precision are in the same library. So if we use no suffix for the impi, it will not overwrite the non-mpi libraries. (Strictly speaking fftw and fftw_cdft libraries are not having the same functions). Anyway, I took the suffix-less behavior from the IMKL easyconfigfile naming conventions. (imkl-11.1.2.144.eb depends on impi, no suffix, and imkl-11.1.2.144-OpenMPI-1.6.5.eb, depends on openmpi)

This is when I was talking that we should make an imkl-11.1.2.144-IMPI.x.y.z.eb version as well and build fftw?_cdft* and we should have an imkl-11-1-2-144.eb which does not have mpi dependence. In fact, imkl can be used without mpi dependence, the only mpi dependenc is in the fftw?_cdft wrappers, that not so often used.