Added clCreateSubDevices implementation for AMD SDK DeviceFission
Changed DeviceFission test to expected pass
Added DeviceFission fixes to AMD SDK patches
Adding sub devices increases parent device's reference count
Fixed buffer allocation problem for memories bigger than 2GB
 - Updated `chunk_slack` function to return only the result of the
comparison and set `last_chunk_size` via a pointer
 - Updated the other functions which use that function
Halide: force linking to the LLVM shared lib as it will be required in the upstream.
Changed coding style
Fix a race condition in the lock initialization.
Merge branch 'master' of github.com:pocl/pocl
Parent device's information copied to sub devices.

Parent device's reference count incremented atomically uding macros POCL_RETAIN_OBJECT and POCL_RELEASE_OBJECT.
Instruct to use the upstream Halide now that the LLVM shared lib
patch was merged in.
benchmark.py: Add Halide cases.
benchmark: Add a 4K image Halide benchmark. The sample is
in public domain:

http://www.uhdwallpapers.org/2014/11/garden-summer-chalet-nature-landscape.html
Disable the custom bufalloc by default for pthread for now.

Halide cases had memory allocation explosions due to it, need to
investigate why.
Fix an issue where pthread malloc allocator freed host
pointers.
Missing backslash.
Download the 4k test image on demand instead of having it
in the git repo.
Typo in the img name.
Include PACKAGE_VERSION and POCL_BUILD_TIMESTAMP in the cache key
hash, do not have a separate file for POCL_BUILD_TIMESTAMP.

Fix a race condition in the cache book keeping lock initialization.
Merge branch 'master' of github.com:volkankeles/pocl