package/mesa3d: enable OpenCL support

package/mesa3d: enable OpenCL support

This patch provides Clover, the OpenCL 1.1 API implementation by Mesa
for AMD GPUs. It generates libOpenCL.so.

Add --disable-opencl-icd because in Mesa 18 it defaults to on.  When
disabled, the shared library is named libOpenCL instead of
libMesaOpenCL and CL headers are installed.

Given that clc headers are being installed to a non-standard location,
it is necessary to specify this path in configure.ac. Otherwise,
pkg-config will output the absolute path to these headers located in
STAGING_DIR, which will cause a runtime error when calling
clBuildProgram.

Signed-off-by: Valentin Korenblit <valentin.korenblit@smile.fr>
Signed-off-by: Valentin Korenblit <valentinkorenblit@gmail.com>
[Thomas:
 - improve the description of the patch, based on input from Romain
 - register as a libopencl provider]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Valentin Korenblit <a class="moz-txt-link-rfc2396E" href="mailto:valentin.korenblit@smile.fr">&lt;valentin.korenblit@smile.fr&gt;</a>
Signed-off-by: Valentin Korenblit <a class="moz-txt-link-rfc2396E" href="mailto:valentinkorenblit@gmail.com">&lt;valentinkorenblit@gmail.com&gt;</a>
Signed-off-by: Thomas Petazzoni <a class="moz-txt-link-rfc2396E" href="mailto:thomas.petazzoni@bootlin.com">&lt;thomas.petazzoni@bootlin.com&gt;</a>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>