Revision 58431

Brings APRUTIL up to speed with recent APR changes that are intended to
eventually make shared builds work on AIX.

- Now creating exports.c and export_vars.h from APR awk scripts.
- Those are used to created exports.lo which can be linked to any
  binary to force all symbols to be "used" so the linker will resolve them.
- Also used to create a list of exported symbols which is necessary for
  linkers like AIX.

I had to explicitly state where to include APR files from, but this may
not be absolutely necessary once I trim out some of the unneeded parts
of make_exports.awk and make_var_export.awk.