llvm: patch for gcc-11 (#28547)

* llvm: patch for gcc-11

- added llvm-gcc11.patch
- adjusted version constraints on existing missing-includes patch.

* remove unnecessary comment

Co-authored-by: Tom Scogland <scogland1@llnl.gov>

var/spack/repos/builtin/packages/llvm/llvm-gcc11.patch

@@ -0,0 +1,9 @@
+--- a/llvm/utils/benchmark/src/benchmark_register.h
++++ b/llvm/utils/benchmark/src/benchmark_register.h
+@@ -2,6 +2,7 @@
+ #define BENCHMARK_REGISTER_H
+ 
+ #include <vector>
++#include <limits>
+ 
+ #include "check.h"

var/spack/repos/builtin/packages/llvm/package.py

@@ -310,7 +310,7 @@ class Llvm(CMakePackage, CudaPackage):
     patch('sanitizer-ipc_perm_mode.patch', when="@5:9+compiler-rt%gcc@9:")
 
     # github.com/spack/spack/issues/24270: MicrosoftDemangle for %gcc@10: and %clang@13:
-    patch('missing-includes.patch', when='@8:9')
+    patch('missing-includes.patch', when='@8')
 
     # Backport from llvm master + additional fix
     # see  https://bugs.llvm.org/show_bug.cgi?id=39696
@@ -342,6 +342,8 @@ class Llvm(CMakePackage, CudaPackage):
     patch('no_cyclades.patch', when='@10:12.0.0')
     patch('no_cyclades9.patch', when='@6:9')
 
+    patch('llvm-gcc11.patch', when='@9:11%gcc@11:')
+
     # Add LLVM_VERSION_SUFFIX
     # https://reviews.llvm.org/D115818
     patch('llvm-version-suffix-macro.patch', when='@:13.0.0')