gnat16Packages.gprbuild{,-boot}: fix build

https://github.com/AdaCore/gprbuild/commit/6421e350274b3018a26bd058b1c90d033b053f71
https://github.com/AdaCore/gprbuild/commit/6b6be939d69d534beb7faca17664d7a1ffa9c81e

Hydra: https://hydra.nixos.org/build/329281640

pkgs/development/ada-modules/gprbuild/boot.nix

@@ -2,6 +2,7 @@
   stdenv,
   lib,
   fetchFromGitHub,
+  fetchpatch2,
   gnat,
   which,
   xmlada, # for src
@@ -36,6 +37,20 @@ stdenv.mkDerivation {
     which
   ];
 
+  # Fix compilation with GNAT 16
+  patches = lib.optionals (lib.versionAtLeast gnat.version "16") [
+    # gpr-compilation-process.adb:44:29: error: operator for type "String" is not declared in "Env_Maps"
+    (fetchpatch2 {
+      url = "https://github.com/AdaCore/gprbuild/commit/6421e350274b3018a26bd058b1c90d033b053f71.patch?full_index=1";
+      hash = "sha256-u9bmr8abmthlyHoeqW5nS2CnaxXmbx6WVwhemxVtw+0=";
+    })
+    # gpr-compilation-protocol.adb:981:13: error: "time_t" is undefined
+    (fetchpatch2 {
+      url = "https://github.com/AdaCore/gprbuild/commit/6b6be939d69d534beb7faca17664d7a1ffa9c81e.patch?full_index=1";
+      hash = "sha256-YUjBvA4bBsrCB46o5WVHOZR6qOf2bkMg+A9qlystDbc=";
+    })
+  ];
+
   postPatch = ''
     # The Makefile uses gprbuild to build gprbuild which
     # we can't do at this point, delete it to prevent the

pkgs/development/ada-modules/gprbuild/default.nix

@@ -47,11 +47,13 @@ stdenv.mkDerivation {
     NIX_LDFLAGS = "-headerpad_max_install_names";
   };
 
-  # Fixes gprbuild being linked statically always. Based on the AUR's patch:
-  # https://aur.archlinux.org/cgit/aur.git/plain/0001-Makefile-build-relocatable-instead-of-static-binary.patch?h=gprbuild&id=bac524c76cd59c68fb91ef4dfcbe427357b9f850
-  patches = lib.optionals (!stdenv.hostPlatform.isStatic) [
-    ./gprbuild-relocatable-build.patch
-  ];
+  patches =
+    gprbuild-boot.patches
+    # Fixes gprbuild being linked statically always. Based on the AUR's patch:
+    # https://aur.archlinux.org/cgit/aur.git/plain/0001-Makefile-build-relocatable-instead-of-static-binary.patch?h=gprbuild&id=bac524c76cd59c68fb91ef4dfcbe427357b9f850
+    ++ lib.optionals (!stdenv.hostPlatform.isStatic) [
+      ./gprbuild-relocatable-build.patch
+    ];
 
   buildFlags = [
     "all"