wcslib: refactor and fix noBrokenSymlinks (#380492)

pkgs/by-name/wc/wcslib/package.nix

@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "ftp://ftp.atnf.csiro.au/pub/software/wcslib/${pname}-${version}.tar.bz2";
-    sha256 = "sha256-lguERCbRSotTze7XgliqkojN7ZmncywGZ8ZPpqUBJtw=";
+    hash = "sha256-lguERCbRSotTze7XgliqkojN7ZmncywGZ8ZPpqUBJtw=";
   };
 
   nativeBuildInputs = [ flex ];
@@ -23,16 +23,25 @@ stdenv.mkDerivation rec {
     "man"
   ];
 
-  meta = with lib; {
+  # DOCDIR is set to the path $out/share/doc/wcslib, and DOCLINK points
+  # to the same location.
+  # `$(LN_S) $(notdir $(DOCDIR)) $(DOCLINK)` effectively running:
+  # `ln -s wcslib $out/share/doc/wcslib`
+  # This produces a broken link because the target location already exists
+  postInstall = ''
+    rm $out/share/doc/wcslib/wcslib
+  '';
+
+  meta = {
     homepage = "https://www.atnf.csiro.au/people/mcalabre/WCS/";
     description = "World Coordinate System library for astronomy";
     longDescription = ''
       Library for world coordinate systems for spherical geometries
       and their conversion to image coordinate systems. This is the
       standard library for this purpose in astronomy.
     '';
-    maintainers = with maintainers; [ hjones2199 ];
-    license = licenses.lgpl3Plus;
-    platforms = platforms.unix;
+    maintainers = with lib.maintainers; [ hjones2199 ];
+    license = lib.licenses.lgpl3Plus;
+    platforms = lib.platforms.unix;
   };
 }