configure: fix check for opencl

add pkg-config support for opencl check.
Signed-off-by: NJun Zhao <mypopydev@gmail.com>

configure

@@ -6135,7 +6135,8 @@ enabled openal            && { { for al_extralibs in "${OPENAL_LIBS}" "-lopenal"
                                die "ERROR: openal not found"; } &&
                              { test_cpp_condition "AL/al.h" "defined(AL_VERSION_1_1)" ||
                                die "ERROR: openal must be installed and version must be 1.1 or compatible"; }
-enabled opencl            && { check_lib opencl OpenCL/cl.h clEnqueueNDRangeKernel -Wl,-framework,OpenCL ||
+enabled opencl            && { check_pkg_config opencl OpenCL CL/cl.h clEnqueueNDRangeKernel ||
+                               check_lib opencl OpenCL/cl.h clEnqueueNDRangeKernel -Wl,-framework,OpenCL ||
                                check_lib opencl CL/cl.h clEnqueueNDRangeKernel -lOpenCL ||
                                die "ERROR: opencl not found"; } &&
                              { test_cpp_condition "OpenCL/cl.h" "defined(CL_VERSION_1_2)" ||