The shorter icu library names are used for WNTMSC only

RepositoryExternal.mk

@@ -372,8 +372,8 @@ endef
 
 else # !SYSTEM_ICU
 
-# icudata and icui18n is called icudt and icuin on Windows :-(
-ifeq ($(OS),WNT)
+# icudata and icui18n is called icudt and icuin when built with MSVC :-(
+ifeq ($(OS)$(COM),WNTMSC)
 $(eval $(call gb_Helper_register_libraries,PLAINLIBS_OOO, \
 	icudt \
 	icuin \

i18npool/Executable_gencoll_rule.mk

@@ -41,7 +41,7 @@ $(eval $(call gb_Executable_add_linked_libs,gencoll_rule,\
 	$(gb_STDLIBS) \
 ))
 
-ifeq ($(OS),WNT)
+ifeq ($(OS)$(COM),WNTMSC)
 $(eval $(call gb_Executable_use_externals,gencoll_rule,\
 	icudt \
 	icuin \

i18npool/Library_i18npool.mk

@@ -56,7 +56,7 @@ $(eval $(call gb_Library_add_linked_libs,i18npool,\
 	$(gb_STDLIBS) \
 ))
 
-ifeq ($(OS),WNT)
+ifeq ($(OS)$(COM),WNTMSC)
 $(eval $(call gb_Library_use_externals,i18npool,\
 	icuin \
 	icuuc \