runtime: fix type descriptor name in C code

I forgot to update the name of the map[string]bool type descriptor
used in go-fieldtrack.c.  This didn't cause any errors because it's a
weak symbol, and the current testsuite has no field tracking tests.

Change-Id: Ic01ccb7e2ad56b948b47ec1ca6a97d72185248a4
Reviewed-on: https://go-review.googlesource.com/91096
Reviewed-by: Than McIntosh <thanm@google.com>
1 file changed