arm64: require armv8.2-a

Author: mszabo-wikia

CMake/HPHPCompiler.cmake

@@ -95,6 +95,8 @@ if (${CMAKE_CXX_COMPILER_ID} STREQUAL "Clang" OR ${CMAKE_CXX_COMPILER_ID} STREQU
   if (IS_X64)
     list(APPEND GENERAL_CXX_OPTIONS "march=x86-64-v3")
     set(CMAKE_ASM_FLAGS  "${CMAKE_ASM_FLAGS} -march=x86-64-v3")
+  elseif (IS_AARCH64)
+    list(APPEND GENERAL_CXX_OPTIONS "march=armv8.2-a")
   endif()
 
   if (${CMAKE_CXX_COMPILER_ID} STREQUAL "Clang" OR ${CMAKE_CXX_COMPILER_ID} STREQUAL "AppleClang") # using Clang