Move _PyUnicode_UTF8() and _PyUnicode_UTF8_LENGTH() outside unicodeobject.h

Move these macros to unicodeobject.c
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 395f146..fe0d4a5 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -105,6 +105,14 @@
         } \
     } while (0)
 
+#define _PyUnicode_UTF8(op)                     \
+    (PyUnicode_IS_COMPACT_ASCII(op) ?           \
+     ((char*)((PyASCIIObject*)(op) + 1)) :      \
+     ((PyCompactUnicodeObject*)(op))->utf8)
+#define _PyUnicode_UTF8_LENGTH(op)                      \
+    (PyUnicode_IS_COMPACT_ASCII(op) ?                   \
+     ((PyASCIIObject*)(op))->length :                   \
+     ((PyCompactUnicodeObject*)(op))->utf8_length)
 #define _PyUnicode_WSTR(op) (((PyASCIIObject*)(op))->wstr)
 #define _PyUnicode_WSTR_LENGTH(op) (((PyCompactUnicodeObject*)(op))->wstr_length)
 #define _PyUnicode_LENGTH(op) (((PyASCIIObject *)(op))->length)