ICU-21210 Fix static builds on Windows

icu4c/source/i18n/unicode/numberrangeformatter.h

diff --git a/icu4c/source/i18n/unicode/numberrangeformatter.h b/icu4c/source/i18n/unicode/numberrangeformatter.h
index dfceeef..d70afc8 100644
--- a/icu4c/source/i18n/unicode/numberrangeformatter.h
+++ b/icu4c/source/i18n/unicode/numberrangeformatter.h
@@ -73,7 +73,7 @@ struct UFormattedNumberRangeImpl;
  * Export an explicit template instantiation. See datefmt.h
  * (When building DLLs for Windows this is required.)
  */
-#if U_PLATFORM == U_PF_WINDOWS && !defined(U_IN_DOXYGEN)
+#if U_PLATFORM == U_PF_WINDOWS && !defined(U_IN_DOXYGEN) && !defined(U_STATIC_IMPLEMENTATION)
 } // namespace icu::number
 U_NAMESPACE_END