Installation error on MacOs: wrong architecture is built

The new `pybind11` version does not install properly on MacOs 10.13.6. During the compilation the linker produces several warnings:

ld: warning: ld: warning: ignoring file build/temp.macosx-10.13-x86_64-3.6/src/wrap_cl.o, file was built for x86_64 which is not the architecture being linked (i386): build/temp.macosx-10.13-x86_64-3.6/src/wrap_cl.oignoring file build/temp.macosx-10.13-x86_64-3.6/src/wrap_constants.o, file was built for x86_64 which is not the architecture being linked (i386): build/temp.macosx-10.13-x86_64-3.6/src/wrap_constants.o
ld: warning: ignoring file build/temp.macosx-10.13-x86_64-3.6/src/wrap_cl_part_1.o, file was built for x86_64 which is not the architecture being linked (i386): build/temp.macosx-10.13-x86_64-3.6/src/wrap_cl_part_1.o
ld: warning: ignoring file build/temp.macosx-10.13-x86_64-3.6/src/wrap_cl_part_2.o, file was built for x86_64 which is not the architecture being linked (i386): build/temp.macosx-10.13-x86_64-3.6/src/wrap_cl_part_2.o
ld: warning: ignoring file build/temp.macosx-10.13-x86_64-3.6/src/wrap_mempool.o, file was built for x86_64 which is not the architecture being linked (i386): build/temp.macosx-10.13-x86_64-3.6/src/wrap_mempool.o
ld: warning: ignoring file build/temp.macosx-10.13-x86_64-3.6/src/bitlog.o, file was built for x86_64 which is not the architecture being linked (i386): build/temp.macosx-10.13-x86_64-3.6/src/bitlog.o
ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/System/Library/Frameworks//OpenCL.framework/OpenCL.tbd, file was built for unsupported file format ( 0x2D 0x2D 0x2D 0x20 0x21 0x74 0x61 0x70 0x69 0x2D 0x74 0x62 0x64 0x2D 0x76 0x33 ) which is not the architecture being linked (i386): /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/System/Library/Frameworks//OpenCL.framework/OpenCL.tbd
ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libSystem.tbd, file was built for unsupported file format ( 0x2D 0x2D 0x2D 0x20 0x21 0x74 0x61 0x70 0x69 0x2D 0x74 0x62 0x64 0x2D 0x76 0x33 ) which is not the architecture being linked (i386): /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libSystem.tbd
ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libc++.tbd, file was built for unsupported file format ( 0x2D 0x2D 0x2D 0x20 0x21 0x74 0x61 0x70 0x69 0x2D 0x74 0x62 0x64 0x2D 0x76 0x33 ) which is not the architecture being linked (i386): /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libc++.tbd
ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/System/Library/Frameworks//OpenCL.framework/OpenCL.tbd, file was built for unsupported file format ( 0x2D 0x2D 0x2D 0x20 0x21 0x74 0x61 0x70 0x69 0x2D 0x74 0x62 0x64 0x2D 0x76 0x33 ) which is not the architecture being linked (x86_64): /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/System/Library/Frameworks//OpenCL.framework/OpenCL.tbd
ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libc++.tbd, file was built for unsupported file format ( 0x2D 0x2D 0x2D 0x20 0x21 0x74 0x61 0x70 0x69 0x2D 0x74 0x62 0x64 0x2D 0x76 0x33 ) which is not the architecture being linked (x86_64): /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libc++.tbd
ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libSystem.tbd, file was built for unsupported file format ( 0x2D 0x2D 0x2D 0x20 0x21 0x74 0x61 0x70 0x69 0x2D 0x74 0x62 0x64 0x2D 0x76 0x33 ) which is not the architecture being linked (x86_64): /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/lib/libSystem.tbd

The installation succeeds despite that, but the module cannot be imported:

>>> import pyopencl
Traceback (most recent call last):
File "", line 1, in
File "/Users/bogdan/.pyenv/versions/3.6.6/lib/python3.6/site-packages/pyopencl/__init__.py", line 37, in
import pyopencl._cl as _cl
ImportError: dlopen(/Users/bogdan/.pyenv/versions/3.6.6/lib/python3.6/site-packages/pyopencl/_cl.cpython-36m-darwin.so, 2): Symbol not found: _clBuildProgram
Referenced from: /Users/bogdan/.pyenv/versions/3.6.6/lib/python3.6/site-packages/pyopencl/_cl.cpython-36m-darwin.so
Expected in: flat namespace
in /Users/bogdan/.pyenv/versions/3.6.6/lib/python3.6/site-packages/pyopencl/_cl.cpython-36m-darwin.so