compiler/types: Making comparing record precision optional

compiler/types: Making comparing record precision optional

On GLES, the interface between vertex and fragment shaders doesn’t
need to have matching precision. This adds an extra argument to
glsl_types::record_compare to disable the precision comparison. This
will later be used for the shader interface check.

In order to make this work this patch also adds a helper function to
recursively compare types while ignoring the precision.

v2: Call record_compare from within compare_no_precision to avoid
    duplicating code (Eric Anholt).

Reviewed-by: Eric Anholt <eric@anholt.net>