postgresql16Packages.pg_similarity: fix build on darwin

Also fixes the build on linux with clang (JIT).

pkgs/servers/sql/postgresql/ext/pg_similarity.nix

@@ -1,4 +1,4 @@
-{ stdenv, lib, fetchFromGitHub, gcc, postgresql, unstableGitUpdater }:
+{ stdenv, lib, fetchFromGitHub, fetchpatch, postgresql, unstableGitUpdater }:
 
 stdenv.mkDerivation {
   pname = "pg_similarity";
@@ -11,7 +11,17 @@ stdenv.mkDerivation {
     sha256 = "sha256-L04ANvyfzHgW7fINeJEY6T77Vojq3SI8P1TWiCRSPs0=";
   };
 
-  buildInputs = [ postgresql gcc ];
+  patches = [
+    (fetchpatch {
+      # https://github.com/eulerto/pg_similarity/pull/43
+      # Also applied in debian as https://sources.debian.org/data/main/p/pg-similarity/1.0-8/debian/patches/pg16
+      name = "pg16.patch";
+      url = "https://github.com/eulerto/pg_similarity/commit/f7781ea5ace80f697a8249e03e3ce47d4b0f6b2f.patch";
+      hash = "sha256-MPDvWfNzSg28lXL5u5/Un9pOCJjqJ4Fz9b8XCfalgts=";
+    })
+  ];
+
+  buildInputs = [ postgresql ];
 
   makeFlags = [ "USE_PGXS=1" ];