Liboffload: Patch for MPSS > 3.4.x

Hello all,

I just added a patch for liboffload to the Phabricator for reviewing:
The patch fixes the build with icc for the liboffload and MPSS versions greater than 3.4. In those versions the structs dim_desc and
arr_desc are defined in the MPSS and not in the liboffload anymore. Furthermore, the directory structure changed. I only tested with
MPSS 3.4.3 (icc 14 and 15), because I don't have any other systems available:
mpss_version=34 mpss_dir=/opt/mpss/3.4.3 compiler_host=icc compiler_target=icc make
Additional, the "-mmic" is set automatically now for compiler_target=icc.