CONFIG: adjust intel compiler and mpi settings (#2056)

- largely as per patch from Jong-Gwan (Jason) Do

NB: the intel-one setup adds in paths for intelmpi.
    Its mpicc version does not harmonize with the OpenFOAM
    system openmpi setup (using mpicc --showme:link).

    Needs adjustment, or use intelmpi instead.

- update name mappings for newer gcc, clang versions

wmake/rules/General/Icx/openmp

@@ -0,0 +1,5 @@
+# Flags for compiling/linking openmp
+# The USE_OMP is for OpenFOAM-specific use (general use is _OPENMP)
+
+COMP_OPENMP = -DUSE_OMP -fiopenmp
+LINK_OPENMP = -fiopenmp