libowfat: fix build with glibc 2.34

pkgs/development/libraries/libowfat/default.nix

@@ -9,6 +9,16 @@ stdenv.mkDerivation rec {
     sha256 = "1hcqg7pvy093bxx8wk7i4gvbmgnxz2grxpyy7b4mphidjbcv7fgl";
   };
 
+  # Fix for glibc 2.34 from Gentoo
+  # https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=914a4aa87415dabfe77181a2365766417a5919a4
+  postPatch = ''
+    # do not define "__pure__", this the gcc builtin (bug #806505)
+    sed 's#__pure__;#__attribute__((__pure__));#' -i fmt.h scan.h byte.h stralloc.h str.h critbit.h || die
+    sed 's#__pure__$#__attrib__pure__#' -i  fmt.h scan.h byte.h stralloc.h str.h critbit.h || die
+    # remove unneeded definition of __deprecated__
+    sed '/^#define __deprecated__$/d' -i scan/scan_iso8601.c scan/scan_httpdate.c || die
+  '';
+
   makeFlags = [ "prefix=$(out)" ];
   enableParallelBuilding = true;
 
@@ -17,8 +27,5 @@ stdenv.mkDerivation rec {
     homepage = "https://www.fefe.de/libowfat/";
     license = licenses.gpl2;
     platforms = platforms.linux;
-    # Doesn't build with glibc 2.34: https://hydra.nixos.org/build/156248131
-    # Should be fixed with the next release: https://bugs.gentoo.org/806505
-    broken = true;
   };
 }