rpm: Implement workaround for DB_BUFFER_SMALL error

rpm: Implement workaround for DB_BUFFER_SMALL error

In certain cases with BerkleyDB 5.3.x we are getting the error:

db3.c:1443: dbcursor->pget(-30999): BDB0063 DB_BUFFER_SMALL: User memory too small fo

See https://bugs.launchpad.net/rpm/+bug/934420 for more information.

It appears to be some type of a bug in the BerkleyDB 5.3.x.  In an attempt
to workaround the problem, when we encounter this situation we attempt
to adjust the size of the mmap buffer until the call works, or we
end up trying 10 times.  The new size is either the updated vp->size
from the failed pget call, or the previous size + 1024.

If DBI debugging is enabled, additional diagnostics are printed, otherwise
a basic retry and success message is added to show that the failure was
resolved.

(From OE-Core rev: bfb2906206158748d0be33baf7984cf885756da1)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>