glsl: Define bit_logic_result_type() in ast_to_hir.cpp

glsl: Define bit_logic_result_type() in ast_to_hir.cpp

This function type checks the operands of and returns the result type of
bit-logic operations.  It replaces the type checking performed in the
following cases of ast_expression::hir() :
    - ast_bit_and
    - ast_bit_or
    - ast_bit_xor