Fix edge-case bugs in kdb5_util load

* fscanf field widths must be less than the buffer size, not equal to
  it.
* Check for negative values of lengths we're going to allocate.
* Eliminate a warning in the comparison of the regexp end offset.
* process_r1_8 policy doesn't actually ignore additional values, so
  get rid of the comment and inequality test suggesting that it does.

https://github.com/krb5/krb5/commit/1c3974c47ad781b7c4b0be9ab7b60316f6ad52c7
Author: Greg Hudson <ghudson@mit.edu>
Commit: 1c3974c47ad781b7c4b0be9ab7b60316f6ad52c7
Branch: master
 src/kadmin/dbutil/dump.c      |   40 +++++++++++++++++++++++++---------------
 src/kadmin/dbutil/kdb5_util.h |    1 -
 2 files changed, 25 insertions(+), 16 deletions(-)