Make the generated configure script additionally report these two checks
with their outcome:
checking for gtk_show_uri function... yes
checking for Gtk::MessageDialog::get_message_area() method... yes
1) Require autoconf >= 2.50
(Released May 2001).
2) Rename file to configure.ac
(Recommended with autoconf >= 2.50).
3) Update macro from AC_TRY_RUN to AC_RUN_IFELSE
(As wanted by the autoupdate program).