Invocations of PolyML can be customised via environment variable or Holmakefile

If you want to provide a maximum heap size with the --maxheap option,
you can do this via something like

  POLY_CLINE_OPTIONS = --maxheap 2000

in a Holmakefile, or by setting an environment variable of the same
name.
Note that Holmakefiles with $(MOSML) commands still usually work under poly
Mention 960e5a1's new POLY_CLINE_OPTIONS facility