glsl: Free the loop state context when we free the loop state.

glsl: Free the loop state context when we free the loop state.

Since this was talloced off of NULL instead of the compile state, it
was a real leak over the course of the program.  Noticed with
valgrind --leak-check=full --show-reachable=yes.  We should really
change these passes to generally get the compile context as an argument
so simple mistakes like this stop mattering.