subsurface: 4.8.2 -> 4.9.3

This bumps subsurface to 4.9.3.

As the subsurface-specific libdivecomputer source is shipped as a git
submodule these days, we can avoid having to fetch a separate tarball
that needs to be kept in sync (and is only uploaded for each release).

This also applies a patch on top of 4.9.3 to properly handle libgit2
versions 1.0 and later - conditional code for older libgit versions has
been removed upstream, but that's a nontrivial backport, which is why
this patch was added.

pkgs/applications/misc/subsurface/default.nix

@@ -4,16 +4,22 @@
 }:
 
 let
-  version = "4.8.2";
+  version = "4.9.3";
+
+  subsurfaceSrc = (fetchFromGitHub {
+    owner = "Subsurface-divelog";
+    repo = "subsurface";
+    rev = "v${version}";
+    sha256 = "1i07f7appifx9j205x5a7ng01wsipxr6n9a3692pm60jli2nsir5";
+    fetchSubmodules = true;
+  });
 
   libdc = stdenv.mkDerivation {
     pname = "libdivecomputer-ssrf";
     inherit version;
 
-    src = fetchurl {
-      url = "https://subsurface-divelog.org/downloads/libdivecomputer-subsurface-branch-${version}.tgz";
-      sha256 = "167qan59raibmilkc574gdqxfjg2f5ww2frn86xzk2kn4qg8190w";
-    };
+    src = subsurfaceSrc;
+    sourceRoot = "source/libdivecomputer";
 
     nativeBuildInputs = [ autoreconfHook ];
 
@@ -70,10 +76,10 @@ in stdenv.mkDerivation {
   pname = "subsurface";
   inherit version;
 
-  src = fetchurl {
-    url = "https://subsurface-divelog.org/downloads/Subsurface-${version}.tgz";
-    sha256 = "1fzrq6rqb6pzs36wxar2453cl509dqpcy9w7nq4gw7b1v2331wfy";
-  };
+  src = subsurfaceSrc;
+
+  # remove with the 4.10 release
+  patches = [ ./0001-core-fix-libgit-ifdef-to-handle-libgit2-v1.0-and-onw.patch ];
 
   buildInputs = [
     libdc googlemaps