build-sys: mark block begin and ends

Done with Egyptian brackets, or K&R style as they are also known.

Change-Id: Ifeaf3ca29be5d4846738ec937ce07728771c5f16
Reviewed-on: http://gerrit.openafs.org/10010
Reviewed-by: Simon Wilkinson <simonxwilkinson@gmail.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>