tests/mtd_flashpage: blacklist native

#15859 exposed a bug in the
handling of FEATURES_REQUIRED_ANY, so #15935
did not run this test, native is currently failing, so blacklist while this
is still the case

tests/mtd_flashpage/Makefile

@@ -3,4 +3,10 @@ include ../Makefile.tests_common
 USEMODULE += mtd_flashpage
 USEMODULE += embunit
 
+# https://github.com/RIOT-OS/RIOT/pull/15859 exposed a bug in the
+# handling of FEATURES_REQUIRED_ANY, so https://github.com/RIOT-OS/RIOT/pull/15935
+# did not run unittests, native is currently failing, so blacklist while this
+# is still the case
+FEATURES_BLACKLIST += arch_native
+
 include $(RIOTBASE)/Makefile.include