fix: pthread weak references in globals.c Linking executables will fail on systems with glibc < 2.34 without declaring these symbols as weak references. In commit c19771c1f13de9196f98260d142d8c8672eb5733 these references were moved to globals.c from threads.c, but the `#pragma weak` declarations were lost in the process. Also removing unneeded weak declarations from threads.c.