Support SVN_HTTP_LIBRARY environment variable for specifying which HTTP library should be used.
Support SVN_HTTP_LIBRARY environment variable for specifying which HTTP library
should be used.

* subversion/libsvn_ra/ra_loader.c
  (svn_ra_open3): Use SVN_HTTP_LIBRARY environment variable if it exists.
   Otherwise use http-library configuration option.

*** Reverted in r34979 ***


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@873841 13f79535-47bb-0310-9956-ffa450edef68

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