hack, declare scm_i_make_primitive_macro() extern

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
cosmetics, shut the compiler up about warnings introduced when switching to guile-2.0

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Revert "hack, declare scm_i_make_primitive_macro() extern"

This reverts commit 7093e6671738703a4ff1ae8dc09f2f99c9139a37.

Hack doesn't work as guile has all symbols emitted with visibility=hidden
hack, try to mimick scm_i_make_primitive_macro()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Revert "hack, try to mimick scm_i_make_primitive_macro()"

This reverts commit dbb9543e743c46841e3a8ab56dab92cecf0dbb52.

Visibility is in our way again.
chore, only support guile-1.8

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'bld/guile-2.0' into next

* bld/guile-2.0:
  chore, only support guile-1.8
  Revert "hack, try to mimick scm_i_make_primitive_macro()"
  hack, try to mimick scm_i_make_primitive_macro()
  Revert "hack, declare scm_i_make_primitive_macro() extern"
  cosmetics, shut the compiler up about warnings introduced when switching to guile-2.0
  hack, declare scm_i_make_primitive_macro() extern