ExternalProject: Always use --non-interactive with svn

The previous commit added --non-interactive as a "side effect"
of turning on SVN_TRUST_CERT. While reviewing that commit, we
decided all ExternalProject svn usage should be non-interactive.

That way, if there's any sort of problem, svn will return an
error right away rather than hang forever waiting for input...

Modules/ExternalProject.cmake

@@ -1049,10 +1049,10 @@ function(_ep_add_download_command name)
       set(svn_user_pw_args ${svn_user_pw_args} "--password=${svn_password}")
     endif()
     if(svn_trust_cert)
-      set(svn_trust_cert_args --non-interactive --trust-server-cert)
+      set(svn_trust_cert_args --trust-server-cert)
     endif()
     set(cmd ${Subversion_SVN_EXECUTABLE} co ${svn_repository} ${svn_revision}
-      ${svn_trust_cert_args} ${svn_user_pw_args} ${src_name})
+      --non-interactive ${svn_trust_cert_args} ${svn_user_pw_args} ${src_name})
     list(APPEND depends ${stamp_dir}/${name}-svninfo.txt)
   elseif(git_repository)
     find_package(Git)
@@ -1205,10 +1205,10 @@ function(_ep_add_update_command name)
       set(svn_user_pw_args ${svn_user_pw_args} "--password=${svn_password}")
     endif()
     if(svn_trust_cert)
-      set(svn_trust_cert_args --non-interactive --trust-server-cert)
+      set(svn_trust_cert_args --trust-server-cert)
     endif()
     set(cmd ${Subversion_SVN_EXECUTABLE} up ${svn_revision}
-      ${svn_trust_cert_args} ${svn_user_pw_args})
+      --non-interactive ${svn_trust_cert_args} ${svn_user_pw_args})
     set(always 1)
   elseif(git_repository)
     if(NOT GIT_EXECUTABLE)