Re-implement the 'warnings' module in C. This allows for usage of the
'warnings' code in places where it was previously not possible (e.g., the
parser). It could also potentially lead to a speed-up in interpreter start-up
if the C version of the code (_warnings) is imported over the use of the
Python version in key places.

Closes issue #1631171.
diff --git a/Misc/NEWS b/Misc/NEWS
index 4319351..eda3685 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -21,6 +21,11 @@
 - zlib.decompressobj().flush(value) no longer crashes the interpreter when
   passed a value less than or equal to zero.
 
+- Issue #1631171: Re-implement the 'warnings' module in C (the original Python
+  code has been kept as backup). This will allow for using the 'warning's
+  machinery in such places as the parser where use of pure Python code is not
+  possible.
+
 Library
 -------