Add more possibilities to call ice4_stepping from ice4_pack

[SebastienRietteMTO]

In mode_ice4_pack, we can compute the microphysics on a selection of points by packing them in new arrays before calling ice4_stepping (LPACK_MICRO=T) or call directly ice4_stepping on all the points (LPACK_MICRO=F).

On NEC, it could be more efficient to use indirection.

This issue describes how to implement an indirection mechanism in the LPACK_MICRO=.F. case. But this way of implementing it was not fully validated by Ryad.

• compute an indirection array (INDIRARRAY), which will be given to ice4_stepping
• in ice4_stepping and lower in the call tree, all "DO JL=1, KSIZE" loops will be transformed into
  "DO JLL=1,KSIZEINDIR; JL=INDIR(JLL, INDIRARRAY)"
• the following piece of code will be included in the different files:
  #ifdef INDIR_MICRO
  #define INDIR(JLL, INDIRARRAY) INDIRARRAY(JLL)
  #else
  #define INDIR(JLL, INDIRARRAY) JLL
  #endif