ecl: import upstream patches for gcc15 compat

Instead of downgrading to C17, import upstream patches for gcc15
compatibility. So downstream packages e.g. sage can build correctly
without setting CFLAGS.

pkgs/development/compilers/ecl/default.nix

@@ -56,11 +56,24 @@ stdenv.mkDerivation rec {
       url = "https://raw.githubusercontent.com/sagemath/sage/9.2/build/pkgs/ecl/patches/write_error.patch";
       sha256 = "0hfxacpgn4919hg0mn4wf4m8r7y592r4gw7aqfnva7sckxi6w089";
     })
+    # Fix gcc15 compat for downstream packages e.g. sage
+    # error: ‘bool’ cannot be defined via ‘typedef’
+    (fetchpatch {
+      url = "https://gitlab.com/embeddable-common-lisp/ecl/-/commit/1aec8f741f69fd736f020b7fe4d3afc33e60ae6a.patch";
+      sha256 = "sha256-/cA6iOOob0ATViQm5EwBbdin5peqRMjLPKa7RjkrJ94=";
+    })
+    # error: too many arguments to function 'fn'; expected 0, have 1
+    (fetchpatch {
+      url = "https://gitlab.com/embeddable-common-lisp/ecl/-/commit/5b4e9c4bbd7cce4a678eecd493e56c495490e8b5.patch";
+      sha256 = "sha256-QHxswFiW2rfDAQ98Sl+VVmyP4M/eIjJWQEcR/B+m398=";
+    })
+    (fetchpatch {
+      url = "https://gitlab.com/embeddable-common-lisp/ecl/-/commit/5ec9e02f6db9694dcdef7574036f1e320d64a8af.patch";
+      sha256 = "sha256-ZRah0IqOt6OQZGqlCq0RKiToyxsRXQEXAiSUGgqZnKU=";
+    })
   ];
 
   configureFlags = [
-    # Fix build with gcc15
-    "CFLAGS=-std=gnu17"
     (if threadSupport then "--enable-threads" else "--disable-threads")
     "--with-gmp-incdir=${lib.getDev gmp}/include"
     "--with-gmp-libdir=${lib.getLib gmp}/lib"