obexd: Fix possible crash while processing pending request

obexd: Fix possible crash while processing pending request

session_process_queue needs to be able to access the request .func in
case an error happen and it later calls pending_request_free so .process
shall not attempt to free the request otherwise it will cause crashes:

Invalid read of size 8
   at 0x4349D2: session_process_queue (session.c:857)
   by 0x434AC5: setpath_complete.isra.1 (session.c:1026)
   by 0x434B29: setpath_cb (session.c:1077)
   by 0x416448: handle_response (gobex.c:1128)
   by 0x41739D: incoming_data (gobex.c:1402)
   by 0x59747FA: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.2)
   by 0x5974B97: ??? (in /usr/lib64/libglib-2.0.so.0.4200.2)
   by 0x5974EC1: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.2)
   by 0x40E23F: main (main.c:322)
 Address 0x66e3d30 is 32 bytes inside a block of size 56 free'd
   at 0x4C2ACE9: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
   by 0x597A50E: g_free (in /usr/lib64/libglib-2.0.so.0.4200.2)
   by 0x4345F5: pending_request_free (session.c:193)
   by 0x4348DF: session_process_setpath (session.c:1131)
   by 0x4349C9: session_process_queue (session.c:854)
   by 0x434AC5: setpath_complete.isra.1 (session.c:1026)
   by 0x434B29: setpath_cb (session.c:1077)
   by 0x416448: handle_response (gobex.c:1128)
   by 0x41739D: incoming_data (gobex.c:1402)
   by 0x59747FA: g_main_context_dispatch (in /usr/lib64/libglib-2.0.so.0.4200.2)
   by 0x5974B97: ??? (in /usr/lib64/libglib-2.0.so.0.4200.2)
   by 0x5974EC1: g_main_loop_run (in /usr/lib64/libglib-2.0.so.0.4200.2)