qemugl makefile has "-L/usr/X11R6/lib" to specifiy the X lib dir.
it is actually obsolate in poky now, because poky use Xserver from
X.org (X11R7.x), and its libs are in standard /usr/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.
