[cmake] Patch tbb for Apple M1 (issue root-project#6903).

Apply patch from uxlfoundation/oneTBB#258

builtins/tbb/patches/apple-m1.patch

@@ -0,0 +1,32 @@
+From 86f6dcdc17a8f5ef2382faaef860cfa5243984fe Mon Sep 17 00:00:00 2001
+From: Yining Karl Li <betajippity@gmail.com>
+Date: Fri, 3 Jul 2020 06:23:18 -0700
+Subject: [PATCH] Add detection of arm64 architecture for macos builds
+
+This commit adds detection of arm64 for macos builds on arm64 hardware.
+The only change necessary is an additional case in the code where
+macos.inc queries and detects the system architecture.
+---
+ build/macos.inc | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/build/macos.inc b/build/macos.inc
+index dde93216..2bdcde7e 100644
+--- a/build/macos.inc
++++ b/build/macos.inc
+@@ -36,11 +36,15 @@ ifndef arch
+      export arch:=ppc32
+    endif
+  else
++  ifeq ($(shell /usr/sbin/sysctl -n hw.machine),arm64)
++   export arch:=arm64
++  else
+    ifeq ($(shell /usr/sbin/sysctl -n hw.optional.x86_64 2>/dev/null),1)
+      export arch:=intel64
+    else
+      export arch:=ia32
+    endif
++  endif
+  endif
+ endif
+

cmake/modules/SearchInstalledSoftware.cmake

@@ -1214,6 +1214,11 @@ if(builtin_tbb)
   elseif(CMAKE_CXX_COMPILER_ID STREQUAL GNU)
     set(_tbb_compiler compiler=gcc)
   endif()
+  if(${ROOT_ARCHITECTURE} MATCHES "macosxarm64")
+    set(tbb_command "patch -p1 -i ${CMAKE_SOURCE_DIR}/builtins/tbb/patches/apple-m1.patch")
+  else()
+    set(tbb_command "")
+  endif()
   if(MSVC)
     set(vsdir "vs2013")
     set(TBB_LIBRARIES ${CMAKE_BINARY_DIR}/lib/tbb.lib)
@@ -1256,6 +1261,7 @@ if(builtin_tbb)
       URL_HASH SHA256=${tbb_sha256}
       INSTALL_DIR ${CMAKE_BINARY_DIR}
       PATCH_COMMAND sed -i -e "/clang -v/s@-v@--version@" build/macos.inc
+      COMMAND ${tbb_command}
       CONFIGURE_COMMAND ""
       BUILD_COMMAND make ${_tbb_compiler} cpp0x=1 "CXXFLAGS=${_tbb_cxxflags}" CPLUS=${CMAKE_CXX_COMPILER} CONLY=${CMAKE_C_COMPILER} "LDFLAGS=${_tbb_ldflags}"
       INSTALL_COMMAND ${CMAKE_COMMAND} -Dinstall_dir=<INSTALL_DIR> -Dsource_dir=<SOURCE_DIR>