Fix the error message to tell which versions of swig are required.
Fix the error message to tell which versions of swig are required.

* build/ac-macros/swig.m4
  Only 1.3.19, 1.3.20 and 1.3.21 work.



git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@852557 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion