Add -z,origin linker flag on OpenBSD.

This is required for $ORIGIN rpath processing here (without having to
fiddle with workarounds like LD_LIBRARY_PATH).

Author: 3405691582

Diff for: CMakeLists.txt

@@ -212,6 +212,10 @@ else()
         "/clang:-fcf-runtime-abi=swift")
 endif()
 
+if(CMAKE_SYSTEM_NAME MATCHES "OpenBSD|DragonFlyBSD")
+    add_link_options("LINKER:-z,origin")
+endif()
+
 if(CMAKE_BUILD_TYPE STREQUAL Debug)
     list(APPEND _Foundation_common_build_flags
         "-DDEBUG")