glsl/glcpp: Add test for a multi-line comment within an #if 0 block

glsl/glcpp: Add test for a multi-line comment within an #if 0 block

This test is written to exercise a bug which I recently wrote, (but
fortunately caught and fixed before ever committing it).

For the curious:

  The bug happened when the NEWLINE_CATCHUP code didn't actually return the
  NEWLINE token (due to the skipping). This resulted in the lexer continuing
  on through all the subsequent rules while still in the NEWLINE_CATCHUP start
  condition, (which then triggered the internal-compiler-error catch-all
  rule).

  What is intended is for the return of the NEWLINE token to start a new
  iteration of the lexer loop, at which time the NEWLINE_CATCHUP-handling code
  will reset from the <NEWLINE_CATCHUP> to the <INITIAL> start condition.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>