Initial support for the vala programming language. * automake.in: Add %known_libraries, lang_vala_rewrite, lang_vala_finish and lang_vala_target_hook to support the Vala programming language. Register Vala language hooks. * lib/am/vala.am: Empty rules file to prevent creation of depend2 based rules for Vala code. * lib/am/Makefile.am (dist_am_DATA): Add vala.am. * m4/vala.m4: Provide AC_PROG_VALAC for detecting the Vala compiler. * m4/Makefile.am (dist_m4data_DATA): Add vala.m4. * tests/vala.test: Test Vala support. * tests/Makefile.am: Update. Signed-off-by: Mathias Hasselmann <mathias.hasselmann@gmx.de> Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>