patch 8.1.0478: cannot build with perl using MinGW

Problem:    Cannot build with perl using MinGW.
Solution:   Add -I. (Ken takata, Cesar Romani)
diff --git a/src/Make_cyg_ming.mak b/src/Make_cyg_ming.mak
index 65a1fbf..e213b80 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -1049,7 +1049,7 @@
 	     $(PERLTYPEMAP) if_perl.xs -output $@
 
 $(OUTDIR)/if_perl.o:	auto/if_perl.c $(INCL)
-	$(CC) -c $(CFLAGS) auto/if_perl.c -o $(OUTDIR)/if_perl.o
+	$(CC) -c $(CFLAGS) -I. auto/if_perl.c -o $(OUTDIR)/if_perl.o
 
 
 $(OUTDIR)/if_ruby.o:	if_ruby.c $(INCL)
diff --git a/src/version.c b/src/version.c
index 1268cdc..4a5c4b7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    478,
+/**/
     477,
 /**/
     476,