runtime: update type descriptor name in fieldtrack C support code

We were using the old name, but nothing noticed because it is a weak
reference that is permitted to be nil, so that it works with code that
does not use the field tracking library.

Change-Id: I0650b96ca3e9f192338920f29d848aff49472e7f
Trust: Ian Lance Taylor <>
Reviewed-by: Cherry Zhang <>
Reviewed-by: Than McIntosh <>
1 file changed