Change all references of svn to git and change revision number to use git hash

[robe]

Right now all branches except for master still have things like svn_repo_revisions.pl instead of repo_revision.pl

so make_dist.sh (even on 3.0 branch is broken since I upgraded it not realizing the repo_revision.pl it needs for git is not present).

Also all the docs still make a lot of references to svn and not git.

GNUMakefile.in also has svn junk.

Working on fixing for 3.0.1 and will backport my changes once done.

[Regina Obe <lr@…>]

In f022046/git:

replace svn number with git has. Back port ​https://git.osgeo.org/gitea/postgis/postgis/pulls/43, add —without-phony, references #4637 references #4617 for PostGIS 3.0.1

[Regina Obe <lr@…>]

In f845dcc/git:

Oops cannot use postgis_lib_version cause it is new, replace back with postgis_svn_version. References #4637 for PostGIS 3.0.1

[Regina Obe <lr@…>]

In 908f288c/git:

Fix snprintf raster to expect string. References #4637 for PostGIS 3.0.1

[Regina Obe <lr@…>]

In 764e52ba/git:

Fix snprintf raster to expect string raster2pgsql. References #4637 for PostGIS 3.0.1

[Regina Obe <lr@…>]

In 98ddd8c/git:

Fix snprintf shp2pgsql pgsql2shp to expect string. References #4637 for PostGIS 3.0.1

[Regina Obe <lr@…>]

In 72c0c0e/git:

Put back postgis lib version accidentally taken out in prior commits. References #4637 for PostGIS 3.0.1