Drop support for sysvinit scripts

As announced by a few releases now, finally drop support for
sysvinit scripts.
Keep rc-local generator for now, as it's really a distinct
feature even though from the same era.

src/basic/build.c

@@ -232,12 +232,6 @@ const char* const systemd_features =
         " -UTMP"
 #endif
 
-#if HAVE_SYSV_COMPAT
-        " +SYSVINIT"
-#else
-        " -SYSVINIT"
-#endif
-
 #if HAVE_LIBARCHIVE
         " +LIBARCHIVE"
 #else