refactoring: rename POSTGIS_MAJOR to POSTGIS_VERSION
refactoring: rename POSTGIS_MAJOR to POSTGIS_VERSION

because it holds both, the major and minor component of the PostGIS version

geometalab/osmaxx-frontend,geometalab/osmaxx-frontend,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/osmaxx,geometalab/osmaxx