Add two patches from ubuntu to fix lto and gcc-11 build failures

debian/patches/D99501-ignore-lto-auto.diff

@@ -0,0 +1,31 @@
+Index: llvm-toolchain-12-12.0.0~++rc3/clang/include/clang/Driver/Driver.h
+===================================================================
+--- llvm-toolchain-12-12.0.0~++rc3.orig/clang/include/clang/Driver/Driver.h
++++ llvm-toolchain-12-12.0.0~++rc3/clang/include/clang/Driver/Driver.h
+@@ -51,7 +51,8 @@ enum LTOKind {
+   LTOK_None,
+   LTOK_Full,
+   LTOK_Thin,
+-  LTOK_Unknown
++  LTOK_Unknown,
++  LTOK_Ignored
+ };
+ 
+ /// Driver - Encapsulate logic for constructing compilation processes
+Index: llvm-toolchain-12-12.0.0~++rc3/clang/lib/Driver/Driver.cpp
+===================================================================
+--- llvm-toolchain-12-12.0.0~++rc3.orig/clang/lib/Driver/Driver.cpp
++++ llvm-toolchain-12-12.0.0~++rc3/clang/lib/Driver/Driver.cpp
+@@ -608,9 +608,12 @@ void Driver::setLTOMode(const llvm::opt:
+   LTOMode = llvm::StringSwitch<LTOKind>(LTOName)
+                 .Case("full", LTOK_Full)
+                 .Case("thin", LTOK_Thin)
++                .Case("auto", LTOK_Ignored)
++                .Case("jobserver", LTOK_Ignored)
+                 .Default(LTOK_Unknown);
+ 
+   if (LTOMode == LTOK_Unknown) {
++    // FIXME: check if argument is a number, then ignore, or handle it
+     assert(A);
+     Diag(diag::err_drv_unsupported_option_argument) << A->getOption().getName()
+                                                     << A->getValue();

debian/patches/fix-missing-include-limit.patch

@@ -0,0 +1,26 @@
+From b498303066a63a203d24f739b2d2e0e56dca70d1 Mon Sep 17 00:00:00 2001
+From: serge-sans-paille <sguelton@redhat.com>
+Date: Tue, 10 Nov 2020 14:55:25 +0100
+Subject: [PATCH] [nfc] Fix missing include
+
+Origin: backport, https://github.com/llvm/llvm-project/commit/b498303066a63a203d24f739b2d2e0e56dca70d1
+Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/llvm-toolchain-11/+bug/1939424
+Applied-Upstream: 12.0.0
+Reviewed-By: Sergio Durigan Junior <sergiodj@ubuntu.com>
+
+---
+ llvm/utils/benchmark/src/benchmark_register.h | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/llvm/utils/benchmark/src/benchmark_register.h b/llvm/utils/benchmark/src/benchmark_register.h
+index 0705e219f2fa..4caa5ad4da07 100644
+--- a/llvm/utils/benchmark/src/benchmark_register.h
++++ b/llvm/utils/benchmark/src/benchmark_register.h
+@@ -1,6 +1,7 @@
+ #ifndef BENCHMARK_REGISTER_H
+ #define BENCHMARK_REGISTER_H
+ 
++#include <limits>
+ #include <vector>
+ 
+ #include "check.h"

debian/patches/series

@@ -147,3 +147,5 @@ D91833-bpftrace-fix-code-gen.diff
 scan-build-py-fix-default-bin.diff
 mesa-texture-failure.patch
 remove-cyclades.diff
+D99501-ignore-lto-auto.diff
+fix-missing-include-limit.patch