Remove X11R6 lib directory

"-L/usr/X11R6/lib" is obsolate in poky. Poky currently use Xserver from X.org (X11R7.x), which puts lib in standard /usr/lib, so no need to specify the extra -L/usr/X11R6/lib. Meanwhile, the -L/usr/X11R6/lib will cause warning: library search path "/usr/X11R6/lib" is unsafe for cross-compilation. so better to remove it.

Signed-off-by: Yu Ke <ke.yu@intel.com>

diff --git a/Makefile b/Makefile
index 9e5a8ea..f3a082a 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ GL_CFLAGS := -Wall -g -O2 -fno-strict-aliasing
 all: libGL.so.1.2
 
 libGL.so.1.2: client_stub.c opengl_client.c glgetv_cst.h opengl_func.h opengl_utils.h opengl_client_xfonts.c mesa_gl.h mesa_glext.h mesa_glx.h mesa_glxext.h
-	$(CC) -fPIC $(GL_CFLAGS) opengl_client.c -shared -o libGL.so.1.2 -lX11 -lXfixes -lm -L$(D)/usr/X11R6/lib -lpthread -I.
+	$(CC) -fPIC $(GL_CFLAGS) opengl_client.c -shared -o libGL.so.1.2 -lX11 -lXfixes -lm -lpthread -I.
 
 opengl_func.h: gl_func.h