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/oct-conf.in.h	Sun Nov 04 16:28:56 2012 -0700
+++ b/libinterp/oct-conf.in.h	Mon Nov 05 01:47:49 2012 +0000
@@ -482,12 +482,16 @@
 #define OCTAVE_CONF_QRUPDATE_LIBS %OCTAVE_CONF_QRUPDATE_LIBS%
 #endif
 
-#ifndef OCTAVE_CONF_QT_INCDIR
-#define OCTAVE_CONF_QT_INCDIR %OCTAVE_CONF_QT_INCDIR%
+#ifndef OCTAVE_CONF_QT_CPPFLAGS
+#define OCTAVE_CONF_QT_CPPFLAGS %OCTAVE_CONF_QT_CPPFLAGS%
 #endif
 
-#ifndef OCTAVE_CONF_QT_LIBDIR
-#define OCTAVE_CONF_QT_LIBDIR %OCTAVE_CONF_QT_LIBDIR%
+#ifndef OCTAVE_CONF_QT_LDFLAGS
+#define OCTAVE_CONF_QT_LDFLAGS %OCTAVE_CONF_QT_LDFLAGS%
+#endif
+
+#ifndef OCTAVE_CONF_QT_LIBS
+#define OCTAVE_CONF_QT_LIBS %OCTAVE_CONF_QT_LIBS%
 #endif
 
 #ifndef OCTAVE_CONF_RANLIB