hla: support setting DCB_DEMCR on resume

This is only minimal support to enable use to catch a Hard Fault in
the stm32l flash bootloader.

Change-Id: I21d6a11893e2f1d173ebff1a651d6f52bf6eec32
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1103
Reviewed-by: Peter Stuge <peter@stuge.se>
Tested-by: jenkins

src/target/hla_target.c

@@ -571,6 +571,11 @@ static int adapter_resume(struct target *target, int current,
 
 	resume_pc = buf_get_u32(pc->value, 0, 32);
 
+	/* write any user vector flags */
+	res = target_write_u32(target, DCB_DEMCR, armv7m->demcr);
+	if (res != ERROR_OK)
+		return res;
+
 	armv7m_restore_context(target);
 
 	/* registers are now invalid */