My Seti@Home Beta tasks error out with this message:
OpenCL platform detected: Intel
OpenCL platform detected: Mesa
OpenCL platform detected: The pocl project
WARNING: BOINC supplied wrong platform!

Boinc Manager messages upon start:
Starting BOINC client version 7.9.3 for x86_64-pc-linux-gnu
Libraries: libcurl/7.58.0 OpenSSL/1.1.0g zlib/1.2.11 libidn2/2.0.4 libpsl/0.19.1 (+libidn2/2.0.4) nghttp2/1.30.0 librtmp/2.3
Data directory: /var/lib/boinc-client
OpenCL: Intel GPU 0: Intel HD Graphics Family (driver version 1.3, device version OpenCL 2.0 beignet 1.3, 4096MB, 4096MB available, 144 GFLOPS peak)
[libc detection] gathered: 2.27, Ubuntu GLIBC 2.27-3ubuntu1
Processor: 4 GenuineIntel Intel(R) Pentium(R) Silver J5005 CPU @ 1.50GHz [Family 6 Model 122 Stepping 1]
OS: Linux LinuxMint: Linux Mint 19.1 Tessa [4.15.0-47-generic|libc 2.27 (Ubuntu GLIBC 2.27-3ubuntu1)]
Memory: 15.32 GB physical, 15.43 GB virtual
VirtualBox version: 5.2.18_Ubuntur123745

Clinfo
Number of platforms 3
Platform Name Intel Gen OCL Driver
Platform Vendor Intel
Platform Version OpenCL 2.0 beignet 1.3
Platform Profile FULL_PROFILE
Platform Extensions cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_byte_addressable_store cl_khr_3d_image_writes cl_khr_image2d_from_buffer cl_khr_depth_images cl_khr_spir cl_khr_icd cl_intel_accelerator cl_intel_subgroups cl_intel_subgroups_short cl_khr_gl_sharing
Platform Extensions function suffix Intel

Platform Name Portable Computing Language
Platform Vendor The pocl project
Platform Version OpenCL 1.2 pocl 1.1 None+Asserts, LLVM 6.0.0, SPIR, SLEEF, DISTRO, POCL_DEBUG
Platform Profile FULL_PROFILE
Platform Extensions cl_khr_icd
Platform Extensions function suffix POCL

Platform Name Clover
Platform Vendor Mesa
Platform Version OpenCL 1.1 Mesa 18.2.8
Platform Profile FULL_PROFILE
Platform Extensions cl_khr_icd
Platform Extensions function suffix MESA

I get the impression that the app either doesn't want to receive 'Intel' as platform name, but 'Beignet', or that it gets 'Beignet' from BOINC and 'Intel' from the OS.

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I cannot help with your problem but I too want to get opencl working in Ubuntu 18.04 with my Intel CPU. This Haswell has "HD Graphics 4600" which should be capable of opencl.

I am currently running 5 RX-560 and 1 RX-570 on a BT85 motherboard and had enough trouble getting the AMD driver to work and am concerned that if I try to get the Intel version of opencl to work I may end up with a broken system with only the CPU crunching.

I am going to follow this thread, maybe someone with more knowledge of Linux drivers can help. Actually just being told that both can work together in version xx with drives x and y would be helpfull