Link for AMD-APP-SDK-v.2.8
Cleanup it a bit.
AMD SDK examples need libSDL, mention it in the README files.
AMD examples: Added info of the 'cmake' requirement and the 'prepare-examples' step.
Fix clCreateKernel with multiple devices

When using multiple devices (POCL_DEVICES="pthread pthread" for
example), clCreateKernel fails with CL_INVALID_PROGRAM_EXECUTABLE.

program.llvm_ir is indexed by device->dev_id.
Initialize and use device’s dev_id

dev_id is never initialized and defaults to 0. Correct code which did
not access device_ptrs with dev_id. Fixes segfault with multiple basic
devices (i.e. POCL_DEVICES="basic basic").
New driver API func. build_hash() for devices to add whatever to kcache hash
Added Visual Studio compatible alignment macros.
Removed ltdl.h when compiling with Visual Studio.
Added Visual Studio implementation for __restrict__
Added Visual Studion implementations for libltdl functions.
Undeclared a define made in Windows.h which conflicts with a goto label.
Fixed preprocessor or/and/not operators to be vc++ compatible.
Added VC++ implementation for lt_dlinit and removed hidden visibility pragma from GET_PROTOTYPES macro.
Removed header from build list to prevent triggering #error in Visual Studio.
Visual Studio does not have include_next.
Added include to get cl_device_id typedef.
Fixed places where unistd.h has been included to include vccompat.hpp on Visual Studio.
Fixed last missing Visual Studio header.
Added snprintf compatibility define.