COMP: adapt mitkPixelTypeMultiplex5 function to make clang compile.
COMP: adapt mitkPixelTypeMultiplex5 function to make clang compile.

Clang complains because a variable could not be set. This is correct since no
else was given in the functions if else block. Now a standard pixeltype of
double is assumed in case no other pixeltype could be correctly determined.
This follows the reasoning already implemented in mitkPixelTypeMultiplex54.

RabadanLab/MITKats,iwegner/MITK,fmilano/mitk,RabadanLab/MITKats,NifTK/MITK,MITK/MITK,fmilano/mitk,MITK/MITK,iwegner/MITK,iwegner/MITK,fmilano/mitk,fmilano/mitk,NifTK/MITK,fmilano/mitk,fmilano/mitk,NifTK/MITK,RabadanLab/MITKats,NifTK/MITK,MITK/MITK,RabadanLab/MITKats,MITK/MITK,iwegner/MITK,iwegner/MITK,NifTK/MITK,fmilano/mitk,iwegner/MITK,MITK/MITK,RabadanLab/MITKats,RabadanLab/MITKats,MITK/MITK,NifTK/MITK