Add -mfma to -mavx2 for clang, and add AVX2 declaration for Zen in DYNAMIC_ARCH builds

cmake/system.cmake

@@ -197,14 +197,14 @@ if (DEFINED TARGET)
   if (${TARGET} STREQUAL SKYLAKEX AND NOT NO_AVX512)
     set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=skylake-avx512")
   endif()
-  if (${TARGET} STREQUAL HASWELL AND NOT NO_AVX2)
+  if ((${TARGET} STREQUAL HASWELL OR ${TARGET} STREQUAL ZEN) AND NOT NO_AVX2)
     if (${CMAKE_C_COMPILER_ID} STREQUAL "GNU")
       execute_process(COMMAND ${CMAKE_C_COMPILER} -dumpversion OUTPUT_VARIABLE GCC_VERSION)
       if (${GCC_VERSION} VERSION_GREATER 4.7 OR ${GCC_VERSION} VERSION_EQUAL 4.7)
         set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -mavx2")
       endif()
     elseif (${CMAKE_C_COMPILER_ID} STREQUAL "CLANG")
-      set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -mavx2")
+      set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -mavx2 -mfma")
     endif()
   endif()
   if (DEFINED HAVE_AVX)