arb_shader_precision: fixed copypasta in description blocks for various tests
arb_shader_precision: corrected filename size calculation
arb_shader_precision: pf parameter to precision_test_fv can be const as well
arb_shader_precision: converted to GL/GLSL 3.3
arb_shader_precision: simplified shader program creation with piglit_build_simple_program()
arb_shader_precision: enable arb_shader_precision in shaders
the shader compiler will issue a warning if the extension is not supported