Dynamically increases the size of hash tables. This is needed for
cleaning the parsing of makeflow. With static sizes and a huge
number of files, all operations were close to linear time, unless
the initial bucket count was made a big number, but this of
course would waste memory for small makeflow files.

git-svn-id: file:///afs/nd.edu/user37/ccl/svn/cctools/trunk@2645 a4d8336d-3463-0410-8bba-c098c45d37a8

(This commit was originally made before cleaning integer types, so a
 small change from uint_64 to UINT_64 was made for 3.7.3)