patch 8.1.1174: cannot build with Ruby 1.8

Problem:    Cannot build with Ruby 1.8. (Tom G. Christensen)
Solution:   Include ruby/st.h. (Ozaki Kiichi, closes #4257)
diff --git a/src/if_ruby.c b/src/if_ruby.c
index 2727524..6779c23 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -118,8 +118,11 @@
 #ifdef RUBY19_OR_LATER
 # include <ruby/encoding.h>
 #endif
+#ifndef RUBY19_OR_LATER
+# include <st.h>  // for ST_STOP and ST_CONTINUE
+#endif
 
-#undef off_t	/* ruby defines off_t as _int64, Mingw uses long */
+#undef off_t	// ruby defines off_t as _int64, Mingw uses long
 #undef EXTERN
 #undef _
 
diff --git a/src/version.c b/src/version.c
index bc12aae..54c15f3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -772,6 +772,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1174,
+/**/
     1173,
 /**/
     1172,