elf: Run constructors on cyclic recursive dlopen (bug 31986)

This is conceptually similar to the reported bug, but does not
depend on auditing.  The fix is simple: just complete execution
of the constructors.  This exposed the fact that the link map
for statically linked executables does not have l_init_called
set, even though constructors have run.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

elf/dl-support.c

@@ -99,6 +99,7 @@ static struct link_map _dl_main_map =
     .l_used = 1,
     .l_tls_offset = NO_TLS_OFFSET,
     .l_serial = 1,
+    .l_init_called = 1,
   };
 
 /* Namespace information.  */