ICU-20872 remove extra ; after function {}

See #888
diff --git a/icu4c/source/i18n/unicode/numberformatter.h b/icu4c/source/i18n/unicode/numberformatter.h
index 6d48f18..42d4687 100644
--- a/icu4c/source/i18n/unicode/numberformatter.h
+++ b/icu4c/source/i18n/unicode/numberformatter.h
@@ -2600,7 +2600,7 @@
     StringByteSink<StringClass> sink(&result);
     toDecimalNumber(sink, status);
     return result;
-};
+}
 #endif // U_HIDE_DRAFT_API
 
 /**