ICU-20836 ICU4C header file plurrule.h needs to include utypes.h before checking U_SHOW_CPLUSPLUS_API.
diff --git a/icu4c/source/i18n/unicode/plurrule.h b/icu4c/source/i18n/unicode/plurrule.h
index 610f288..a155356 100644
--- a/icu4c/source/i18n/unicode/plurrule.h
+++ b/icu4c/source/i18n/unicode/plurrule.h
@@ -18,10 +18,10 @@
 #ifndef PLURRULE
 #define PLURRULE
 
-#if U_SHOW_CPLUSPLUS_API
-
 #include "unicode/utypes.h"
 
+#if U_SHOW_CPLUSPLUS_API
+
 /**
  * \file
  * \brief C++ API: PluralRules object