Remove reference to no longer existing file win32.c

Backport from master

Change-Id: I165c958213dd120b7fe894cc7a11a64b94698370
Reviewed-on: http://review.couchbase.org/25214
Reviewed-by: Bin Cui <bin.cui@gmail.com>
Tested-by: Bin Cui <bin.cui@gmail.com>