Issue #18513: Add workaround for OS X 10.8 cexp bug that leads to wrong cmath.rect...

diff --cc Misc/NEWS
index 9e6c5558a36ae09c3c9a2c5b78c5910219179dd1,f79f62584aa83cac4aa61490fde851b856e53cde..f24fc9126bfe7dc5befbffcc026a406f46e635cd
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -159,9 -49,9 +159,12 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #18513: Fix behaviour of cmath.rect w.r.t. signed zeros on OS X 10.8 +
+   gcc.
+ 
 +- Issue #18479: Changed venv Activate.ps1 to make deactivate a function, and
 +  removed Deactivate.ps1.
 +
  - Issue #18480: Add missing call to PyType_Ready to the _elementtree extension.
  
  - Issue #17778: Fix test discovery for test_multiprocessing. (Patch by