Need a help: building UDUNITS on VAX

Hi, netcdfgroup

I'm trying to build udunits library and udunits executable on VAX, but
have no luck.   There are several Unix standard C functions are not
avaliable on VAX:   alloca,  getopt, bcopy, tsearch, tfind, and twalk.
I have found some of soruce codes but not tsearch, tfind and twalk.

If anyone has successfully built udunits library and udunits executalbe
on VAX, I would like to hear form you.   Or if anyone knows where I can
find the source code for tsearch, tfind and twalk please let me know.
(I have already searched several public domains "libc" directory.)

Thank you.

- Willa