Replace os/win32/mod_dll.c and modules/standard/mod_so.c with a single

unified mod_so. The required dynamic loading functions are abstracted
in os/{win32,unix}/os.h to these manifest constants:

  os_dl_module_handle_type    type of handle returned by os_dl_load
  os_dl_load(l)               load a file
  os_dl_unload(l)             unload a file
  os_dl_sym(h,s)              find address of a symbol
  os_dl_error()               get last os_dl_*() call error as a string

Reviewed by:	Randy Terbush and Martin Kraemer (untested)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@80307 13f79535-47bb-0310-9956-ffa450edef68