Fix pattern to detect i386-based OpenBSD system type

Fix pattern to detect i386-based OpenBSD system type

When the pattern to detect OpenBSD system types (via MKAFS_OSTYPE) was split
into two separate ones for amd64 and i386 architectures, the pattern for
i386-based systems was not set quite right. As a result, i386-based OpenBSD
systems are no longer detected properly at this stage, resulting in an error
of "cannot find input file: src/libafs/MakefileProto..in" during configure.
This patch corrects the pattern.

Change-Id: I67079af74117fa3cdc765f19944e23223709ae6b
Reviewed-on: http://gerrit.openafs.org/1897
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>