src/poky:ccache: Upgrade to v3.3.4

Only the copyright year has been updated in LICENSE.txt. The license text
itself has not changed.

This version fixes a bug with dependency output that could cause problems
when compiling kernels for different MACHINEs using a shared ccache. See
ccache/ccache#158

(From OE-Core rev: 01751da07a6822f0b5d1c08bb73cc7ef376e39b7)

Signed-off-by: Mike Crowe <mac@mcrowe.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>