Fix crash in ARC assignment.
Fix crash in ARC assignment.

Reported by Banlu Name-of-the-week!



davidchisnall/libobjc2,crystax/android-vendor-libobjc2,ngrewe/libobjc2,crystax/android-vendor-libobjc2,ngrewe/libobjc2,darlinghq/darling-libobjc2,darlinghq/darling-libobjc2,davidchisnall/libobjc2,gnustep/libobjc2,gnustep/libobjc2