Update ObjFW to 0.90.2, from Jonathan Schleifer in PR pkg/52645.

ObjFW 0.90.1 -> ObjFW 0.90.2, 23.10.2017
* Fix shadowed variables which caused many bugs (e.g. using the wrong object)
* Many, many nullability fixes
* OFTCPSocket: Fix exception not being retained for async connect
* OFThread: Fix setting the name on the wrong thread
* OFMutableSet: Fix missing override for -[copy]
* configure: Fix posix_spawnp check
* Xcode project: Set the correct version for the bridge
* Better check for iOS
* tests: Fix testing the wrong OFKernelEventObserver

ObjFW 0.90 -> ObjFW 0.90.1, 20.08.2017
* OFData: Fix -[description]
* OFFileManager: Set errno to 0 before readdir()
* OFDate: Add -[localMinute]
* OFTarArchiveEntry: Fix prefix handling for ustar
* OFZIPArchive: Fix uncompressed + data descriptor
* OFArray: Fix MessagePack encoding
* of_asprintf: Don't require set up OFLocalization
* OFGZIPStream: Add missing documentation
* Fix a linker warning on OpenBSD/SPARC64
* Remove the OFFile b modes from MorphOS
  (they were already removed for all other OSes)

(bsiegert)