CL: Fix entrypoint validation for ICDs For some OpenCL ICD implementations, the clGetPlatformIDs API is left as nullptr in the ICD dispatch table. This is because the OpenCL ICD Loader instead uses the clIcdGetPlatformIDsKHR call instead. Updating the passthrough code to only require checking the clGetPlatformIDs API if the platform is not an ICD. Bug: angleproject:42266872 Change-Id: Ic723adbf3ad0f6c79389ef629dd24ae8a82ca9ba Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5789651 Commit-Queue: Austin Annestrand <a.annestrand@samsung.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>