blosc2 fails to link on OpenBSD

Ref: https://github.com/HDFGroup/hdf5/pull/6198#pullrequestreview-4232473318

```
[ 99%] Linking C static library ../../../bin/libblosc2.a
Merging bundled dependency archives into libblosc2.a
/usr/bin/ar: error: script line 4: could not parse library: The file was not recognized as a valid object file
CMake Error at /home/runner/work/actions/actions/plugins-build/_deps/blosc2-src/cmake/merge_static_libs.cmake:75 (message):
Failed to merge static libraries into
/home/runner/work/actions/actions/plugins-build/bin/libblosc2.a
Call Stack (most recent call first):
merge_blosc2_static_Release.cmake:7 (include)

*** Error 1 in . (_deps/blosc2-build/blosc/CMakeFiles/blosc2_static.dir/build.make:439 'bin/libblosc2.a')
*** Error 2 in . (CMakeFiles/Makefile2:2177 '_deps/blosc2-build/blosc/CMakeFiles/blosc2_static.dir/all')
*** Error 2 in /home/runner/work/actions/actions/plugins-build (Makefile:166 'all': /usr/bin/make -s -f CMakeFiles/Makefile2 all)
```