cmd/link: RISC-V external link, failed to find text symbol for HI20 relocation [1.22 backport]

[gopherbot]

@cherrymui requested issue #65646 to be considered for backport to the next 1.22 minor release.

I think it is reasonable to backport. Internal linking is not the default mode, and has limitations.

@gopherbot please backport this to Go 1.22. Thanks.

[gopherbot]

Change https://go.dev/cl/568157 mentions this issue: [release-branch.go1.22] cmd/link/internal/riscv64: generate local text symbols for R_RISCV_CALL

[mknyszek]

This seems safe. The fix is confined to the RISC-V codebase and fixes a real issue (code won't build when externally linked) with no workaround. Approved.

[gopherbot]

Closed by merging 7fb7acb to release-branch.go1.22.