bpo-37445: Include FORMAT_MESSAGE_IGNORE_INSERTS in FormatMessageW() calls (GH-14462)

If FormatMessageW() is passed the FORMAT_MESSAGE_FROM_SYSTEM flag without FORMAT_MESSAGE_IGNORE_INSERTS, it will fail if there are insert sequences in the message definition.

Misc/NEWS.d/next/Windows/2019-06-28-18-10-29.bpo-37445.LsdYO6.rst

+Include the ``FORMAT_MESSAGE_IGNORE_INSERTS`` flag in ``FormatMessageW()``
+calls.

Modules/_ctypes/callproc.c

@@ -242,7 +242,9 @@ static WCHAR *FormatError(DWORD code)
 {
     WCHAR *lpMsgBuf;
     DWORD n;
-    n = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
+    n = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+                       FORMAT_MESSAGE_FROM_SYSTEM |
+                       FORMAT_MESSAGE_IGNORE_INSERTS,
                        NULL,
                        code,
                        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), /* Default language */

Modules/overlapped.c

@@ -500,7 +500,8 @@ overlapped_FormatMessage(PyObject *ignore, PyObject *args)
         return NULL;
 
     n = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER |
-                       FORMAT_MESSAGE_FROM_SYSTEM,
+                       FORMAT_MESSAGE_FROM_SYSTEM |
+                       FORMAT_MESSAGE_IGNORE_INSERTS,
                        NULL,
                        code,
                        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),

PC/bdist_wininst/install.c

@@ -938,7 +938,8 @@ static BOOL SystemError(int error, char *msg)
         LPVOID lpMsgBuf;
         FormatMessage(
             FORMAT_MESSAGE_ALLOCATE_BUFFER |
-            FORMAT_MESSAGE_FROM_SYSTEM,
+            FORMAT_MESSAGE_FROM_SYSTEM |
+            FORMAT_MESSAGE_IGNORE_INSERTS,
             NULL,
             error,
             MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),