Only have one build rule for budb_errs.c

This commit squashes two cherry-picks from master together, as the
first one broke the build with pthreaded ubik enabled.

The first commit:
    Author: Simon Wilkinson <sxw@your-file-system.com>
    Date:   Mon Feb 21 00:29:33 2011 +0000
    budb: Only have one build rule for budb_errs.c

    budb had two build rules that could produce budb_errs.c, but only
    one of them also produced budb_client.h. This led to problems with
    parallel makes, as depending on which rule fired first, budb_client.h
    might, or might not, exist.

    Rework all of this so that it's cleaner. Instead of producing two
    copies of the error table, just make budb_client.h a static file,
    and include the dynamically generated budb_errs.h from it. This
    reduces code duplication, and means that we have to run compile_et
    one less time.

    Reviewed-on: http://gerrit.openafs.org/4027
    Tested-by: Derrick Brashear <shadow@dementia.org>
    Reviewed-by: Derrick Brashear <shadow@dementia.org>
    (cherry picked from commit 0d0b5048a5b68d4079b13609775f9234183d1947)

The second commit:
    Author: Andrew Deason <adeason@sinenomine.net>
    Date:   Mon Feb 21 13:49:59 2011 -0600
    Fix budb build rules for tbudb and WINNT

    Commit 0d0b5048a5b68d4079b13609775f9234183d1947 only fixed the budb
    Makefile.in. Make the analagous changes to tbudb/Makefile.in and
    NTMakefile.

    Reviewed-on: http://gerrit.openafs.org/4029
    Tested-by: BuildBot <buildbot@rampaginggeek.com>
    Reviewed-by: Derrick Brashear <shadow@dementia.org>
    (cherry picked from commit 61453d8f33f6508f8464ffba0657aefb6c7eae3b)

Change-Id: I7d35c7557bcd82ba50742f2594bd4bb78cf0e5a5
Reviewed-on: http://gerrit.openafs.org/9405
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>