gnu: LLVM: Add missing include statement for compatibility with GCC 11.

* gnu/packages/patches/llvm-8-missing-include.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/llvm.scm (llvm-11, llvm-10, llvm-9, llvm-8)[source](patches):
Add it.

gnu/local.mk

@@ -1443,6 +1443,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/llvm-3.6-fix-build-with-gcc-10.patch	\
   %D%/packages/patches/llvm-3.x.1-fix-build-with-gcc.patch	\
   %D%/packages/patches/llvm-8-fix-build-with-gcc-10.patch	\
+  %D%/packages/patches/llvm-8-missing-include.patch		\
   %D%/packages/patches/llvm-9-fix-bitcast-miscompilation.patch	\
   %D%/packages/patches/llvm-9-fix-lpad-miscompilation.patch	\
   %D%/packages/patches/llvm-9-fix-scev-miscompilation.patch	\

gnu/packages/llvm.scm

@@ -866,6 +866,7 @@ with that of libgomp, the GNU Offloading and Multi Processing Library.")
      (origin
       (method url-fetch)
       (uri (llvm-uri "llvm" version))
+      (patches (search-patches "llvm-8-missing-include.patch"))
       (sha256
        (base32
         "0s94lwil98w7zb7cjrbnxli0z7gklb312pkw74xs1d6zk346hgwi"))))))
@@ -899,6 +900,7 @@ with that of libgomp, the GNU Offloading and Multi Processing Library.")
      (origin
       (method url-fetch)
       (uri (llvm-uri "llvm" version))
+      (patches (search-patches "llvm-8-missing-include.patch"))
       (sha256
        (base32
         "1wydhbp9kyjp5y0rc627imxgkgqiv3dfirbqil9dgpnbaw5y7n65"))))
@@ -943,6 +945,7 @@ with that of libgomp, the GNU Offloading and Multi Processing Library.")
         (base32
          "16hwp3qa54c3a3v7h8nlw0fh5criqh0hlr1skybyk0cz70gyx880"))
        (patches (search-patches
+                 "llvm-8-missing-include.patch"
                  "llvm-9-fix-bitcast-miscompilation.patch"
                  "llvm-9-fix-scev-miscompilation.patch"
                  "llvm-9-fix-lpad-miscompilation.patch"))))
@@ -986,7 +989,8 @@ with that of libgomp, the GNU Offloading and Multi Processing Library.")
               (sha256
                (base32
                 "1rvm5gqp5v8hfn17kqws3zhk94w4kxndal12bqa0y57p09nply24"))
-              (patches (search-patches "llvm-8-fix-build-with-gcc-10.patch"))))
+              (patches (search-patches "llvm-8-fix-build-with-gcc-10.patch"
+                                       "llvm-8-missing-include.patch"))))
     (license license:ncsa)))
 
 (define-public clang-runtime-8

gnu/packages/patches/llvm-8-missing-include.patch

@@ -0,0 +1,17 @@
+Add missing include statement for compatibility with libstdc++ 11.
+
+Taken from upstream:
+
+  https://github.com/llvm/llvm-project/commit/b498303066a63a203d24f739b2d2e0e56dca70d1
+
+diff --git a/utils/benchmark/src/benchmark_register.h b/utils/benchmark/src/benchmark_register.h
+--- a/utils/benchmark/src/benchmark_register.h
++++ b/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"