fix const warnings

- and use proper accessor fn for target_id

examples/multiplex/margo-example-mp-server.c

@@ -24,7 +24,7 @@
 static void my_rpc_shutdown_ult(hg_handle_t handle)
 {
     hg_return_t hret;
-    struct hg_info *hgi;
+    const struct hg_info *hgi;
     margo_instance_id mid;
 
     //printf("Got RPC request to shutdown\n");

examples/multiplex/svc1-client.c

@@ -38,7 +38,7 @@ void svc1_do_thing(margo_instance_id mid, hg_addr_t svr_addr, uint32_t mplex_id)
     int ret;
     hg_size_t size;
     void* buffer;
-    struct hg_info *hgi;
+    const struct hg_info *hgi;
 
     /* allocate buffer for bulk transfer */
     size = 512;
@@ -57,7 +57,7 @@ void svc1_do_thing(margo_instance_id mid, hg_addr_t svr_addr, uint32_t mplex_id)
         HG_BULK_READ_ONLY, &in.bulk_handle);
     assert(ret == 0);
 
-    hgi->target_id = mplex_id;
+    HG_Set_target_id(handle, mplex_id);
 
     /* Send rpc. Note that we are also transmitting the bulk handle in the
      * input struct.  It was set above. 
@@ -86,7 +86,7 @@ void svc1_do_other_thing(margo_instance_id mid, hg_addr_t svr_addr, uint32_t mpl
     int ret;
     hg_size_t size;
     void* buffer;
-    struct hg_info *hgi;
+    const struct hg_info *hgi;
 
     /* allocate buffer for bulk transfer */
     size = 512;
@@ -105,7 +105,7 @@ void svc1_do_other_thing(margo_instance_id mid, hg_addr_t svr_addr, uint32_t mpl
         HG_BULK_READ_ONLY, &in.bulk_handle);
     assert(ret == 0);
 
-    hgi->target_id = mplex_id;
+    HG_Set_target_id(handle, mplex_id);
 
     /* Send rpc. Note that we are also transmitting the bulk handle in the
      * input struct.  It was set above. 

examples/multiplex/svc1-server.c

@@ -18,7 +18,7 @@ static void svc1_do_thing_ult(hg_handle_t handle)
     hg_size_t size;
     void *buffer;
     hg_bulk_t bulk_handle;
-    struct hg_info *hgi;
+    const struct hg_info *hgi;
     margo_instance_id mid;
     ABT_thread my_ult;
     ABT_xstream my_xstream; 
@@ -77,7 +77,7 @@ static void svc1_do_other_thing_ult(hg_handle_t handle)
     hg_size_t size;
     void *buffer;
     hg_bulk_t bulk_handle;
-    struct hg_info *hgi;
+    const struct hg_info *hgi;
     margo_instance_id mid;
     ABT_thread my_ult;
     ABT_xstream my_xstream; 

examples/multiplex/svc2-server.c

@@ -18,7 +18,7 @@ static void svc2_do_thing_ult(hg_handle_t handle)
     hg_size_t size;
     void *buffer;
     hg_bulk_t bulk_handle;
-    struct hg_info *hgi;
+    const struct hg_info *hgi;
     margo_instance_id mid;
     ABT_thread my_ult;
     ABT_xstream my_xstream; 
@@ -77,7 +77,7 @@ static void svc2_do_other_thing_ult(hg_handle_t handle)
     hg_size_t size;
     void *buffer;
     hg_bulk_t bulk_handle;
-    struct hg_info *hgi;
+    const struct hg_info *hgi;
     margo_instance_id mid;
     ABT_thread my_ult;
     ABT_xstream my_xstream;