Add support to connect Arm Development Studio IDE to FVP on local runs.

This patch adds the environment variable "connect_debugger" to CI:

     * When connect_debugger == 0 (default), CI will work as usual.
     * When connect_debugger == 1, CI will
       - Call FVP with the -S flag enabled, so it can connect
       	 to ARM DS IDE for debugging sessions.
       - Set test_run variable to 1, overriding any manual
         setting for this variable.
       - Build TF-A with SPIN_ON_BL1 flag enabled.

Change-Id: I300b9babc28c0d4752bf3352ca3599da14f34edb
Signed-off-by: Javier Almansa Sobrino <javier.almansasobrino@arm.com>
diff --git a/model/fvp_common.sh b/model/fvp_common.sh
index d1a47a9..59d8254 100644
--- a/model/fvp_common.sh
+++ b/model/fvp_common.sh
@@ -20,6 +20,7 @@
 reset_var reset_to_spmin
 reset_var secure_memory
 reset_var secure_ram_fill
+reset_var wait_debugger
 
 
 if [ "$bl2_at_el3" ]; then
@@ -34,6 +35,8 @@
 -C bp.ve_sysregs.exit_on_shutdown=1
 -C pctl.startup=$pctl_startup
 
+${wait_debugger+-S}
+
 ${secure_memory+-C bp.secure_memory=$secure_memory}
 ${cache_state_modelled+-C cache_state_modelled=$cache_state_modelled}