treewide: reenable LTO on i686

pkgs/applications/misc/curaengine/stable.nix

@@ -13,8 +13,6 @@ stdenv.mkDerivation {
 
   postPatch = ''
     substituteInPlace Makefile --replace "--static" ""
-  '' + lib.optionalString stdenv.isi686 ''
-    substituteInPlace Makefile --replace "-flto" ""
   '';
 
   installPhase = ''

pkgs/applications/virtualization/OVMF/default.nix

@@ -30,10 +30,6 @@ edk2.mkDerivation projectDscPath {
 
   hardeningDisable = [ "format" "stackprotector" "pic" "fortify" ];
 
-  # Fails on i686 with:
-  # 'cc1: error: LTO support has not been enabled in this configuration'
-  NIX_CFLAGS_COMPILE = lib.optionals stdenv.isi686 [ "-fno-lto" ];
-
   buildFlags =
     lib.optionals secureBoot [ "-D SECURE_BOOT_ENABLE=TRUE" ]
     ++ lib.optionals csmSupport [ "-D CSM_ENABLE" "-D FD_SIZE_2MB" ]

pkgs/development/libraries/amdvlk/default.nix

@@ -65,9 +65,6 @@ in stdenv.mkDerivation rec {
 
   cmakeDir = "../drivers/xgl";
 
-  # LTO is disabled in gcc for i686 as of #66528
-  cmakeFlags = lib.optionals stdenv.is32bit ["-DXGL_ENABLE_LTO=OFF"];
-
   installPhase = ''
     install -Dm755 -t $out/lib icd/amdvlk${suffix}.so
     install -Dm644 -t $out/share/vulkan/icd.d icd/amd_icd${suffix}.json

pkgs/servers/klipper/default.nix

@@ -15,12 +15,6 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-vUhP71vZ5XFG7MDkPFpAcCUL4kIdzHJ1hAkwqIi6ksQ=";
   };
 
-  # We have no LTO on i686 since commit 22284b0
-  postPatch = lib.optionalString stdenv.isi686 ''
-    substituteInPlace chelper/__init__.py \
-      --replace "-flto -fwhole-program " ""
-  '';
-
   sourceRoot = "source/klippy";
 
   # there is currently an attempt at moving it to Python 3, but it will remain

pkgs/tools/system/efibootmgr/default.nix

@@ -22,8 +22,6 @@ stdenv.mkDerivation rec {
       sha256 = "1sbijvlpv4khkix3vix9mbhzffj8lp8zpnbxm9gnzjz8yssz9p5h";
     })
   ];
-  # We have no LTO here since commit 22284b07.
-  postPatch = if stdenv.isi686 then "sed '/^CFLAGS/s/-flto//' -i Make.defaults" else null;
 
   makeFlags = [ "EFIDIR=nixos" "PKG_CONFIG=${stdenv.cc.targetPrefix}pkg-config" ];