cmd/internal/obj: remove pointless validation
cmd/internal/obj: remove pointless validation

s.Func.Text only can be nil at the moment, otherwise there has
some bugs in compiler's Go rumtime.

Change-Id: Ib2ff9bb977352838e67f2b98a69468f6f350c1f3
Reviewed-on: https://go-review.googlesource.com/123535
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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