Based on this report, I am adding a FUNC_MAX_ARGS define to

src/include/pg_config.h.win32.  Certainly if we have INDEX_MAX_KEYS in
there, we should have FUNC_MAX_ARGS too.

Report from Chris Ryan

src/include/pg_config.h.win32

@@ -19,6 +19,7 @@
 #define BLCKSZ	8192
 
 #define INDEX_MAX_KEYS		16
+#define FUNC_MAX_ARGS		INDEX_MAX_KEYS
 
 #define HAVE_ATEXIT
 #define HAVE_MEMMOVE