GH-49292: [C++] Add support for armv8 or later

Author: kou

cpp/cmake_modules/SetupCxxFlags.cmake

@@ -28,10 +28,10 @@ if(NOT DEFINED ARROW_CPU_FLAG)
     set(ARROW_CPU_FLAG "emscripten")
   elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "AMD64|amd64|X86|x86|i[3456]86|x64")
     set(ARROW_CPU_FLAG "x86")
-  elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|ARM64|arm64")
-    set(ARROW_CPU_FLAG "aarch64")
-  elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm$|armv[4-7]")
+  elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm$|armv[4-7]|armv8l")
     set(ARROW_CPU_FLAG "aarch32")
+  elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|ARM64|arm64|armv")
+    set(ARROW_CPU_FLAG "aarch64")
   elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "powerpc|ppc")
     set(ARROW_CPU_FLAG "ppc")
   elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "s390x")