Build xdemos programs by default on linux-dri

Since libglut is no longer hardcoded, we can build the xdemos programs
so long as a GLX enabled libGL and libGLU have been built.

configs/linux-dri

@@ -55,10 +55,10 @@ USING_EGL=0
 # Directories
 ifeq ($(USING_EGL), 1)
 SRC_DIRS = egl glx/x11 mesa glu glut/glx glw
-PROGRAM_DIRS = egl
+PROGRAM_DIRS = egl xdemos
 else
 SRC_DIRS = glx/x11 mesa glu glut/glx glw
-PROGRAM_DIRS =
+PROGRAM_DIRS = xdemos
 endif
 
 DRIVER_DIRS = dri

configs/linux-dri-xcb

@@ -55,10 +55,10 @@ USING_EGL=0
 # Directories
 ifeq ($(USING_EGL), 1)
 SRC_DIRS = egl glx/x11 mesa glu glut/glx glw
-PROGRAM_DIRS = egl
+PROGRAM_DIRS = egl xdemos
 else
 SRC_DIRS = glx/x11 mesa glu glut/glx glw
-PROGRAM_DIRS =
+PROGRAM_DIRS = xdemos
 endif
 
 DRIVER_DIRS = dri