Use pkg-config to discover Qt (pkg-config is already a requirement anyway). * build-aux/common.mk (do_subst_config_vals): Replace QT_INCDIR and QT_LIBDIR with QT_CPPFLAGS, QT_LDFLAGS and QT_LIBS. * configure.ac: Likewise and use pkg-config to discover the new variables. * libgui/Makefile.am (QT_INCDIR, QT_LIBDIR, QT_LIBS, QT_LDFLAGS): Delete variable definitions. * libgui/link-deps.mk (LIBOCTGUI_LINK_DEPS): Use automake @QT_LIBS@. (LIBOCTGUI_LIK_OPTS): Use automake @QT_LDFLAGS@. * libgui/qterminal-module.mk (qterminal_libqterminal_la_CPPFLAGS): Use automake @QT_CPPFLAGS@ instead of QT_INCDIR-based include paths. (MOC_CPPFLAGS): Define Q_OS_WIN32 instead of WIN32. * libgui/src/module.mk (src_libgui_src_la_CPPFLAGS): Use automake @QT_CPPFLAGS@ instead of QT_INCDIR-based include paths. * libinterp/interpfcn/toplev.cc (Foctave_config_info): Replace QT_INCDIR and QT_LIBDIR with QT_CPPFLAGS, QT_LDFLAGS and QT_LIBS. * libinterp/oct-conf.in.h: Replace OCTAVE_CONF_QT_INCDIR and OCTAVE_CONF_QT_LIBDIR with OCTAVE_CONF_QT_CPPFLAGS, OCTAVE_CONF_QT_LDFLAGS and OCTAVE_CONF_QT_LIBS. * m4/acinclude.m4 (OCTAVE_CHECK_FUNC_FINDFIRST_MODERN, OCTAVE_CHECK_FUNC_SETPLACEHOLDERTEXT): Use QT_CPPFLAGS instead of QT_INCDIR.

--- a/libinterp/interpfcn/toplev.cc	Sun Nov 04 16:28:56 2012 -0700
+++ b/libinterp/interpfcn/toplev.cc	Mon Nov 05 01:47:49 2012 +0000
@@ -1346,8 +1346,9 @@
       { false, "QRUPDATE_CPPFLAGS", OCTAVE_CONF_QRUPDATE_CPPFLAGS },
       { false, "QRUPDATE_LDFLAGS", OCTAVE_CONF_QRUPDATE_LDFLAGS },
       { false, "QRUPDATE_LIBS", OCTAVE_CONF_QRUPDATE_LIBS },
-      { false, "QT_INCDIR", OCTAVE_CONF_QT_INCDIR },
-      { false, "QT_LIBDIR", OCTAVE_CONF_QT_LIBDIR },
+      { false, "QT_CPPFLAGS", OCTAVE_CONF_QT_CPPFLAGS },
+      { false, "QT_LDFLAGS", OCTAVE_CONF_QT_LDFLAGS },
+      { false, "QT_LIBS", OCTAVE_CONF_QT_LIBS },
       { false, "RANLIB", OCTAVE_CONF_RANLIB },
       { false, "RDYNAMIC_FLAG", OCTAVE_CONF_RDYNAMIC_FLAG },
       { false, "READLINE_LIBS", OCTAVE_CONF_READLINE_LIBS },