Fix compiler warnings in master

When compiling current master with --enable-gcc-warnings set, I get the following errors:

connection_edge.c: In function ‘connection_edge_process_inbuf’:
connection_edge.c:160: error: format ‘%ld’ expects type ‘long int’, but argument 7 has type ‘size_t’
connection_edge.c: In function ‘connection_ap_handshake_send_begin’:
connection_edge.c:2444: error: format ‘%ld’ expects type ‘long int’, but argument 5 has type ‘size_t’
connection_edge.c:2444: error: format ‘%ld’ expects type ‘long int’, but argument 6 has type ‘size_t’

I changed %ld into %d in those lines in my sources which made the warnings go away. But I'm not sure if that's the right fix, which is why I didn't attach a patch.