fix cmake

  * enable fp16 feature correctly with gcc on x86/x86_64

cmake/OpenCVCompilerOptions.cmake

@@ -170,9 +170,6 @@ if(CMAKE_COMPILER_IS_GNUCXX)
         add_extra_compiler_option(-mfma)
       endif()
     endif()
-    if((X86 OR X86_64) AND NOT MSVC)
-        add_extra_compiler_option(-mf16c)
-    endif((X86 OR X86_64) AND NOT MSVC)
 
     # GCC depresses SSEx instructions when -mavx is used. Instead, it generates new AVX instructions or AVX equivalence for all SSEx instructions when needed.
     if(NOT OPENCV_EXTRA_CXX_FLAGS MATCHES "-mavx")
@@ -204,6 +201,9 @@ if(CMAKE_COMPILER_IS_GNUCXX)
         add_extra_compiler_option(-mpopcnt)
       endif()
     endif()
+    if((X86 OR X86_64) AND NOT MSVC)
+        add_extra_compiler_option(-mf16c)
+    endif((X86 OR X86_64) AND NOT MSVC)
   endif(NOT MINGW)
 
   if(X86 OR X86_64)