Proj documentation says new functions not available til 7.1 but we have at 7.0

[robe]

This was brought to my attention.

I haven't checked to see if we are in trouble, and the docs are wrong or we need to up this requirement

In ​https://git.osgeo.org/gitea/postgis/postgis/src/branch/master/postgis/lwgeom_transform.c#L224 We have proj_context_get_user_writable_directory guarded with a PROJ ≥ 70

but according to PROJ documentation that function was added in PROJ 7.1 ​https://proj.org/en/7.1/development/reference/functions.html

I don't think we have any bots testing PROJ 7.0, and I actually don't know anyone running PROJ 7.0 in production, so it's possible it is broken for 7.0.

I'm going to whip up a 7.0 to confirm it's broken for 7.0

[robe]

Confirmed this doesn't work on proj 7.0, get error when compiling against proj 7.0.1

lwgeom_transform.o: In function `postgis_proj_version':
C:\ming64gcc81\projects\postgis\postgis-git\postgis/lwgeom_transform.c:221: undefined reference to `proj_context_get_url_endpoint'
C:\ming64gcc81\projects\postgis\postgis-git\postgis/lwgeom_transform.c:224: undefined reference to `proj_context_get_user_writable_directory'
C:\ming64gcc81\projects\postgis\postgis-git\postgis/lwgeom_transform.c:222: undefined reference to `proj_context_get_url_endpoint'
C:\ming64gcc81\projects\postgis\postgis-git\postgis/lwgeom_transform.c:224: undefined reference to `proj_context_get_user_writable_directory'
C:\ming64gcc81\projects\postgis\postgis-git\postgis/lwgeom_transform.c:225: undefined reference to `proj_context_get_user_writable_directory'

[Regina Obe <lr@…>]

In d7b5845/git:

New Proj variables only available in 7.1+ and not 7.0+
References #5482 for PostGIS 3.5.0

[Regina Obe <lr@…>]

In 2a34b1c1/git:

New Proj variables only available in 7.1+ and not 7.0+
Closes #5482 for PostGIS 3.4.1