package/snappy: bump version, switch to cmake

package/snappy: bump version, switch to cmake

Upstream switched to CMake, host-pkgconf is not needed anymore.

Instead of using the latest release 1.1.6 we use current git HEAD
because it contains important patches:

"Support both static and shared library CMake builds."
https://github.com/google/snappy/commit/c756f7f5d90ad7591d4f96bb0da8159634943359

"Redo CMake configuration", this commit allows to disable building
Snappy's own tests.
https://github.com/google/snappy/commit/be6dc3db83c4701e3e79694dcbfd1c3da03b91dd

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>