ignore more build artefact

Author: remicollet

.gitignore

@@ -19,15 +19,18 @@ config.status
 config.sub
 configure
 configure.in
+configure.ac
 http.la
 install-sh
 lcov_data
 libtool
 ltmain.sh
+ltmain.sh.backup
 missing
 mkinstalldirs
 modules/
 *.lo
+*.la
 *.o
 run-tests.php
 tests/*.diff