Issue #578. When supplying own libOpenCL.so with -DENABLE_ICD=1 the CHECK_FUNCTION_EXISTS fails because OPENCL_FOUND variable has been already set by the previous call to pkg_check_modules. This is rectified by explicitly unsetting OPENCL_FOUND.
Issue #578. When supplying own libOpenCL.so with -DENABLE_ICD=1 the CHECK_FUNCTION_EXISTS
fails because OPENCL_FOUND variable has been already set by the previous call to
pkg_check_modules. This is rectified by explicitly unsetting OPENCL_FOUND.

Oblomov/pocl,franz/pocl,pocl/pocl,franz/pocl,Oblomov/pocl,pocl/pocl,Oblomov/pocl,pocl/pocl,Oblomov/pocl,franz/pocl,pocl/pocl,pocl/pocl,franz/pocl,franz/pocl,Oblomov/pocl