Limit attrlen to 128K.

Closes Coverity #982085
Check for NULL.

Closes Coverity #982083 (false positive)
value may be NULL.  Only for admin mistake.

Closes Coverity #982082
Check for NULL da.  Only if dictionary files are broken.

Closes Coverity #982081
Remove dead code.

Closes Coverity #982080, 982079
Don't free data returned from gdbm_fetch

Closes Coverity #982067, 982068, 982069
Use correct flag for check

Closes Coverity #982078
Remove dead code.

Closes Coverity #982077
Remove dead code

Closes Coverity #982076