fatal error: CL/opencl.h: No such file or directory

[martinl]

When compiling GDAL (trunk) I realized that opencl.h is not correctly checked when configuring GDAL.

...
checking for OpenCL support... yes
...
  OpenCL support:            yes

make install

/bin/bash /home/martin/src/gdal/libtool --mode=compile --tag=CXX g++ -Wall  -g -DDEBUG  -Wall  -I/home/martin/src/gdal/port -I/home/martin/src/gdal/gcore -I/home/martin/src/gdal/alg -I/home/martin/src/gdal/ogr -I/home/martin/src/gdal/ogr/ogrsf_frmts -DHAVE_GEOS=1 -I/usr/local/include -DOGR_ENABLED -I/home/martin/src/gdal/port  -DHAVE_OPENCL -c -o gdalwarpkernel.lo gdalwarpkernel.cpp
libtool: compile:  g++ -Wall -g -DDEBUG -Wall -I/home/martin/src/gdal/port -I/home/martin/src/gdal/gcore -I/home/martin/src/gdal/alg -I/home/martin/src/gdal/ogr -I/home/martin/src/gdal/ogr/ogrsf_frmts -DHAVE_GEOS=1 -I/usr/local/include -DOGR_ENABLED -I/home/martin/src/gdal/port -DHAVE_OPENCL -c gdalwarpkernel.cpp  -fPIC -DPIC -o .libs/gdalwarpkernel.o
In file included from gdalwarpkernel.cpp:34:0:
gdalwarpkernel_opencl.h:41:23: fatal error: CL/opencl.h: No such file or directory
compilation terminated.
make[1]: *** [gdalwarpkernel.lo] Error 1
make[1]: Leaving directory `/home/martin/src/gdal/alg'
make: *** [core-target] Error 2

[Even Rouault]

trunk r25071 "Unix configure: better detection of OpenCL headers and library (#4665)"