The current build script for OpenBSD does not properly detect SSE2 support in the host CPU. It checks if the machine hardware name is x86_64, which is not a name that OpenBSD uses for any architecture. What uname on Linux reports as x86_64, OpenBSD's uname reports as amd64.
This new build script detects whether the host CPU is AMD64, and in that case defines UI_SSE2.
The current build script for OpenBSD does not properly detect SSE2 support in the host CPU. It checks if the machine hardware name is x86_64, which is not a name that OpenBSD uses for any architecture. What uname on Linux reports as x86_64, OpenBSD's uname reports as amd64.
This new build script detects whether the host CPU is AMD64, and in that case defines UI_SSE2.