cmd/link: put runtime.framepointer_enabled in DATA instead of RODATA
cmd/link: put runtime.framepointer_enabled in DATA instead of RODATA

On darwin, only writable symbol is exported
(cmd/link/internal/ld/macho.go:/machoShouldExport).
For plugin to work correctly, global variables, including
runtime.framepointer_enabled which is set by the linker, need
to be exported when dynamic linking. Put it in DATA so it is
exported. Also in Go it is defined as a var, which is not
read-only.

While here, do the same for runtime.goarm.

Fixes #24653.

Change-Id: I9d1b7d5a648be17103d20b97be65a901cb69f5a2
Reviewed-on: https://go-review.googlesource.com/104715
Run-TryBot: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>

CAFxX/go,CAFxX/go,Cofyc/go,josharian/go,nawawi/go,cloudflare/go,CAFxX/go,nawawi/go,cloudflare/go,cloudflare/go,josharian/go,golang/go,golang/go,nawawi/go,nawawi/go,nawawi/go,Cofyc/go,golang/go,akutz/go,akutz/go,Cofyc/go,josharian/go,golang/go,CAFxX/go,cloudflare/go,Cofyc/go,golang/go,CAFxX/go,Cofyc/go,josharian/go,cloudflare/go,cloudflare/go,akutz/go,cloudflare/go,akutz/go,CAFxX/go,josharian/go,golang/go,cloudflare/go,akutz/go,Cofyc/go,golang/go,Cofyc/go,akutz/go,golang/go,CAFxX/go,CAFxX/go,Cofyc/go,nawawi/go,nawawi/go,josharian/go,josharian/go,josharian/go,nawawi/go,akutz/go,akutz/go