libmtp 1.1.6.

The 1.1.6 upgrade introduces a bunch of fixes in libmtp as well as a
host of new supported devices. Most notably the Windows Phone 8 series
of devices, the Nexus 4 and the read/write extensions of Google Androids
MTP stack.

Closes #19883.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
libmtp: does not compile on Snow Leopard if libgcrypt is linked