patch 8.1.0419: Cygwin: running cproto fails with -O2

Problem:    Cygwin: running cproto fails with -O2.
Solution:   Strip -O2 for cproto. (Ken Takata, closes #3465)
diff --git a/src/Makefile b/src/Makefile
index 9c19281..5b25e03 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2028,8 +2028,9 @@
 # them as a list of individual flags.
 # The -E"gcc -E" argument must be separate to avoid problems with shell
 # quoting.
+# Strip -O2, it may cause cproto to write stderr to the file "2".
 CPROTO = cproto $(PROTO_FLAGS) -DPROTO \
-	 `echo '$(LINT_CFLAGS)' | sed -e 's/ -[a-z-]\+//g'`
+	 `echo '$(LINT_CFLAGS)' | sed -e 's/ -[a-z-]\+//g' -e 's/ -O[^ ]\+//g'`
 
 ### Would be nice if this would work for "normal" make.
 ### Currently it only works for (Free)BSD make.
diff --git a/src/version.c b/src/version.c
index 079657e..bc3cbf3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    419,
+/**/
     418,
 /**/
     417,