make new feature-specific guards overridable by user #defines in CPython to...

make new feature-specific guards overridable by user #defines in CPython to allow switching them on and off for testing/debugging/benchmarking

Cython/Utility/ModuleSetupCode.c

@@ -35,23 +35,44 @@
 #ifdef PYPY_VERSION
   #define CYTHON_COMPILING_IN_PYPY 1
   #define CYTHON_COMPILING_IN_CPYTHON 0
+  #undef CYTHON_USE_TYPE_SLOTS
   #define CYTHON_USE_TYPE_SLOTS 0
+  #undef CYTHON_USE_PYLIST_INTERNALS
   #define CYTHON_USE_PYLIST_INTERNALS 0
+  #undef CYTHON_USE_UNICODE_INTERNALS
   #define CYTHON_USE_UNICODE_INTERNALS 0
+  #undef CYTHON_AVOID_BORROWED_REFS
   #define CYTHON_AVOID_BORROWED_REFS 1
+  #undef CYTHON_ASSUME_SAFE_MACROS
   #define CYTHON_ASSUME_SAFE_MACROS 0
+  #undef CYTHON_UNPACK_METHODS
   #define CYTHON_UNPACK_METHODS 0
+  #undef CYTHON_FAST_THREAD_STATE
   #define CYTHON_FAST_THREAD_STATE 0
 #else
   #define CYTHON_COMPILING_IN_PYPY 0
   #define CYTHON_COMPILING_IN_CPYTHON 1
-  #define CYTHON_USE_TYPE_SLOTS 1
-  #define CYTHON_USE_PYLIST_INTERNALS 1
-  #define CYTHON_USE_UNICODE_INTERNALS 1
-  #define CYTHON_AVOID_BORROWED_REFS 0
-  #define CYTHON_ASSUME_SAFE_MACROS 1
-  #define CYTHON_UNPACK_METHODS 1
-  #define CYTHON_FAST_THREAD_STATE 1
+  #ifndef CYTHON_USE_TYPE_SLOTS
+    #define CYTHON_USE_TYPE_SLOTS 1
+  #endif
+  #ifndef CYTHON_USE_PYLIST_INTERNALS
+    #define CYTHON_USE_PYLIST_INTERNALS 1
+  #endif
+  #ifndef CYTHON_USE_UNICODE_INTERNALS
+    #define CYTHON_USE_UNICODE_INTERNALS 1
+  #endif
+  #ifndef CYTHON_AVOID_BORROWED_REFS
+    #define CYTHON_AVOID_BORROWED_REFS 0
+  #endif
+  #ifndef CYTHON_ASSUME_SAFE_MACROS
+    #define CYTHON_ASSUME_SAFE_MACROS 1
+  #endif
+  #ifndef CYTHON_UNPACK_METHODS
+    #define CYTHON_UNPACK_METHODS 1
+  #endif
+  #ifndef CYTHON_FAST_THREAD_STATE
+    #define CYTHON_FAST_THREAD_STATE 1
+  #endif
 #endif
 
 #if !defined(CYTHON_USE_PYLONG_INTERNALS) && CYTHON_COMPILING_IN_CPYTHON && PY_VERSION_HEX >= 0x02070000