Better generateMipmap error reporting.
Better generateMipmap error reporting.

svn path=/branches/libavg_libav09/; revision=9340

libavg/libavg,yyd01245/libavg,th3infinity/libavg,th3infinity/libavg,th3infinity/libavg,hoodie/libavg,yyd01245/libavg,scotty007/libavg,yyd01245/libavg,hoodie/libavg,hoodie/libavg,scotty007/libavg,th3infinity/libavg,libavg/libavg,yyd01245/libavg,scotty007/libavg,hoodie/libavg,scotty007/libavg,libavg/libavg,libavg/libavg