Fix non-standard test feature test collection. I.e. make the feature

collection no rely on implementioned defined behaviour. And fix check
program handling of no-expression invocations vs expression invocations.

include/boost/predef/library/std/sgi.h

@@ -45,8 +45,7 @@ If available version number as major, minor, and patch.
 
 #define BOOST_LIB_STD_SGI_NAME "SGI"
 
+#endif
+
 #include <boost/predef/detail/test.h>
 BOOST_PREDEF_DECLARE_TEST(BOOST_LIB_STD_SGI,BOOST_LIB_STD_SGI_NAME)
-
-
-#endif