[PSyData] Simplify building psydata libraries with original lfric infrastructure

[hiker]

The directory layout of the internal infrastructure library and the LFRic infrastructure library is inconsistent, e.g. LFRic uses field/field_mod.o, mesh/mesh.o (and same for .mod files). Our copy of the infrastructure is all in a flat directory. That means that it's not that easy to replace our infrastructure library with current LFRic (ours is outdated and not compatible anymore).

I could build the extract library using:

LFRIC_INF_DIR=$HOME/work/lfric/trunk/gungho/working/gungho/field make

put it there had been any dependency on (say) mesh.mod, it would be impossible to simply replace the infrastructure library.

Either make the Makefile smarter (maybe copy the lfric .o and .mod files into a build directory??), or add a similar directory structure to our copy (have field, mesh, ... subdirectories)