Remove (deprecated) GPI-2 threads tests

See merge request rui.machado/gpi-2!22

Some config fix

See merge request rui.machado/gpi-2!19

We are deprecating the gpi2 threads. This is another step in that
direction, before removing the implementation.

Issue 56

See merge request rui.machado/gpi-2!21

 Simplify common operations/definitions.

Included again for some reason in f1986d53

Main point: append correctly default C/FC options to those specified
by the user.

Issue 52

See merge request rui.machado/gpi-2!16

The variable `rw_list_elem_max` can setup arbitrarily at a
configuration step, but still must be less than GASPI_RW_LIST_ELEM_MAX
(which is defined as 255). `list_usermelems` is used for testing those
features in `gaspi_write_list`.

Config add missing spec fields

See merge request rui.machado/gpi-2!12

Autotools add ccomps

See merge request rui.machado/gpi-2!18

Dynamic seg and groups allocation

See merge request rui.machado/gpi-2!13

- instead of constant, use user provided number in config for
  allocation.