Throw an error if we are building with qt support and the qt libs are not found.

Bug #188275 r=timeless

configure

@@ -11085,9 +11085,9 @@ if eval "test \"`echo '$ac_cv_lib_'$ac_lib_var`\" = yes"; then
   QT_LIB=-lqt-mt
 else
   echo "$ac_t""no" 1>&6
+{ echo "configure: error: Cannot find QT libraries." 1>&2; exit 1; }
 fi
 
-    
 fi
 
     LDFLAGS=$_SAVE_LDFLAGS

configure.in

@@ -3152,8 +3152,8 @@ then
     AC_LANG_SAVE
     AC_LANG_CPLUSPLUS
     AC_CHECK_LIB(qt, main, QT_LIB=-lqt,
-      AC_CHECK_LIB(qt-mt, main, QT_LIB=-lqt-mt)
+        AC_CHECK_LIB(qt-mt, main, QT_LIB=-lqt-mt,
-    )
+            AC_MSG_ERROR([Cannot find QT libraries.])))
     LDFLAGS=$_SAVE_LDFLAGS
     QT_LIBS="-L/usr/X11R6/lib $QT_LDFLAGS $QT_LIB -lXext -lX11"
 dnl    AM_PATH_QT($QT_VERSION,,