linker: allow debugging of constructors

This patch allows the debugging of constructors in shared
libraries and executables. It does so by ensuring that the
corresponding binary is visible to gdb before running the
constructors.

Change-Id: I0a3df726a04ad109944c834dcbba672b85d3991e
diff --git a/linker/linker.c b/linker/linker.c
index 00f36c0..fdb7981 100644
--- a/linker/linker.c
+++ b/linker/linker.c
@@ -2039,8 +2039,8 @@
      */
     if (program_is_setuid)
         nullify_closed_stdio ();
-    call_constructors(si);
     notify_gdb_of_load(si);
+    call_constructors(si);
     return 0;
 
 fail: