package/libclc: new package

package/libclc: new package

This patch provides libclc, an open source implementation of the
library requirements of the OpenCL C programming language, as
specified by the OpenCL 1.1 Specification. It is intended to be used
with Clover (Mesa3D's OpenCL implementation for AMD GPUs.

It needs to be compiled with host-clang, as it generates LLVM IR bitcode
files containing device builtin functions for each target.

Currently, libclc supports AMDGCN, R600 and NVPTX targets.

As OpenCL kernels can be built dynamically on the target using libclang and
libLLVM, it is necessary to have clc headers installed on the target. Buildroot
removes /usr/include in its target-finalize step, so clc headers are installed to
/usr/share/clc.

Signed-off-by: Valentin Korenblit <valentin.korenblit@smile.fr>
Signed-off-by: Valentin Korenblit <valentinkorenblit@gmail.com>
Reviewed-by: Romain Naour <romain.naour@smile.fr>
[Thomas:
 - fix license information as noticed by Romain
 - add comment to explain why --includedir=/usr/share is used]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>