Android patch: Enable test UFIELD_CATEGORY_LIST_SPAN in IntlTestWithFieldPosition::checkMixedFormattedValue

It fixes the static analysis founding in http://b/145129186#comment7
This CL should later be upstreamed.

Bug: 145129186
Test: atest CtsIcu4cTestCases
Change-Id: I6730a3353e86e9e703aa9a1f628c365a1900c1fb
diff --git a/icu4c/source/test/intltest/formattedvaluetest.cpp b/icu4c/source/test/intltest/formattedvaluetest.cpp
index 0edf420..3502d11 100644
--- a/icu4c/source/test/intltest/formattedvaluetest.cpp
+++ b/icu4c/source/test/intltest/formattedvaluetest.cpp
@@ -241,7 +241,7 @@
     assertFalse(baseMessage + u"A after loop again: " + CFPosToUnicodeString(cfpos), afterLoopResult);
 
     // Check nextPosition constrained over each category one at a time
-    for (int32_t category=0; category<UFIELD_CATEGORY_COUNT+1; category++) {
+    for (int32_t category=0; category<=UFIELD_CATEGORY_COUNT+1; category++) {
         if (category == UFIELD_CATEGORY_COUNT+1) {
             category = UFIELD_CATEGORY_LIST_SPAN;
         }