versioner: don't always hide future decls.

Bug: http://b/32748732
Test: python run_tests.py
Change-Id: I8f799015ebb1017f5e7d1324fb4c724e12a268bc
diff --git a/tools/versioner/tests/preprocessor/headers/foo.h b/tools/versioner/tests/preprocessor/headers/foo.h
index 7eba47f..81c8b4b 100644
--- a/tools/versioner/tests/preprocessor/headers/foo.h
+++ b/tools/versioner/tests/preprocessor/headers/foo.h
@@ -40,3 +40,5 @@
     __INTRODUCED_IN_64(22);
 
 int group_lp32() __INTRODUCED_IN_ARM(12) __INTRODUCED_IN_X86(12) __INTRODUCED_IN_MIPS(12);
+
+int future() __INTRODUCED_IN_FUTURE;