Switch to Py_FFI_COMPLEX_AVAILABLE and tweak the comdition

Author: encukou

Modules/_ctypes/cfield.c

@@ -1436,7 +1436,7 @@ for base_code, base_c_type in [
 
     TABLE_ENTRY_SW(d, &ffi_type_double);
 #if defined(Py_HAVE_C_COMPLEX) && defined(Py_FFI_SUPPORT_C_COMPLEX)
-    if (have_ffi_complex()) {
+    if (Py_FFI_COMPLEX_AVAILABLE) {
         TABLE_ENTRY(C, &ffi_type_complex_double);
         TABLE_ENTRY(E, &ffi_type_complex_float);
         TABLE_ENTRY(F, &ffi_type_complex_longdouble);

Modules/_ctypes/ctypes.h

@@ -9,13 +9,13 @@
 // For Apple's libffi, this must be determined at runtime (see gh-128156).
 #if defined(Py_HAVE_C_COMPLEX) && defined(Py_FFI_SUPPORT_C_COMPLEX)
 #   include "../_complex.h"       // complex
-#   if defined(__APPLE__) && USING_APPLE_OS_LIBFFI && defined(__has_builtin)
-#       define have_ffi_complex() (__builtin_available(macOS 10.15, *))
+#   if USING_APPLE_OS_LIBFFI && defined(__has_builtin) && __has_builtin(__builtin_available)
+#       define Py_FFI_COMPLEX_AVAILABLE __builtin_available(macOS 10.15, *)
 #   else
-#       define have_ffi_complex() 1
+#       define Py_FFI_COMPLEX_AVAILABLE 1
 #   endif
 #else
-#   define have_ffi_complex() 0
+#   define Py_FFI_COMPLEX_AVAILABLE 0
 #endif
 
 #ifndef MS_WIN32