FWIW I can't reproduce the segfault by running through glsl_compiler. I do,
however, get a

0:35(1): error: #extension directive is not allowed in the middle of a shader

But that should be work-around-able with a driconf setting (or by running the
game with allow_glsl_extension_directive_midshader=1 in the environment). When
I move the #extension line up, no complaints (other than the unknown
GL_ATI_draw_buffers thing), nothing in valgrind either.

Perhaps you can capture an apitrace of the issue?