glsl: Generate correct ir_binop_vector_extract code for out and inout parameters

glsl: Generate correct ir_binop_vector_extract code for out and inout parameters

Like with type conversions on out parameters, some extra copies need to
occur to handle these cases.  The fundamental problem is that
ir_binop_vector_extract is not an lvalue, but out and inout parameters
must be lvalues.  A previous patch delt with a similar problem in the
LHS of ir_assignment.

v2: Convert tabs to spaces.  Suggested by Eric.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>