runtime: weak.Pointer.Value fails to link

A program that calls weak.Pointer.Value() fails to link because weak.runtime_makeStrongFromWeak is missing. This also blocks the Go standard library TLS certificate cache.

Run tinygo run testdata/weak.go with Go 1.24 or later, using the small reproducer from #5633. The original Darwin/arm64 report shows linker could not find symbol _weak.runtime_makeStrongFromWeak. The expected output is weak value: 42.

Source checked on 18 September 2026. dev at 93940cb6 still has the registration hook but lacks the conversion hook. This report covers the missing symbol. Weak pointer collection behavior needs separate work.

#5633 was closed on 17 September with a request for this issue. Hosted TLS selection in #5635 depends on this hook.

Replacement draft PR #5698.