put a setting to use a smaller texture size to reduce rtos common mem error

[lina654321]

hi,
first i like to say all those involve in developing the app has done a very good job. i can play some psp game on samsung galaxy y(rooted) almost at 60 at speed with some tweak done on ppsspp.ini.however, i face problem where the app mostly hang due to battle scene in game and system log contain rtos common error. when I google it it seem this problem relate to memory usage by egl for texture. I hope you can include a setting in graphic to reduce the texture size one or two step notch down from current texture size. maybe it can used to fix other game with graphic issue