Issue #13522: document error return values of some float and complex C API functions.

diff --cc Misc/ACKS
index 20d1ef1e9dd5abe57707867afaa2211e4c1b1194,10f138676d7f3dc7a796e0e21e735b4d421b25d1..a2eed830875a68e987f04f8656e2b87722575dcf
--- 1/Misc/ACKS
--- 2/Misc/ACKS
+++ b/Misc/ACKS
@@@ -147,8 -138,8 +147,9 @@@ Alastair Bur
  Tarn Weisner Burton
  Lee Busby
  Ralph Butler
 +Nicolas Cadou
  Jp Calderone
+ Arnaud Calmettes
  Daniel Calvelo
  Tony Campbell
  Brett Cannon