log: print filename and line number

[prife]

add more information when logging, like this

[20:55:03.616][3] main.c:719 enabling libimobiledevice logging
[20:55:03.616][3] main.c:730 usbmuxd v1.1.2 starting up
[20:55:03.616][4] main.c:838 Creating socket
[20:55:03.616][4] main.c:196 Preparing a Unix socket
[20:55:03.616][4] main.c:202 Binding to socket
[20:55:03.616][4] main.c:223 Starting to listen on socket
[20:55:03.616][4] main.c:933 Initializing USB
[20:55:03.616][3] usb.c:852 Using libusb 1.0.21
[20:55:03.618][4] usb.c:877 Registering for libusb hotplug events
[20:55:03.618][4] usb.c:418 Found new device with v/p 05ac:12a8 at 1-14
[20:55:03.618][4] usb.c:514 Found interface 1 with endpoints 04/85 for device 1-14
[20:55:03.618][4] usb.c:574 Using wMaxPacketSize=512 for device 1-14
[20:55:03.618][4] usb.c:594 USB Speed is 480 MBit/s for device 1-14
[20:55:03.618][4] main.c:938 1 device detected
[20:55:03.618][3] main.c:940 Initialization complete
[20:55:03.618][4] client.c:261 Client 12 accepted: /usr/lib/gvfs/gvfs-afc-volume-monitor[4254]