cmd/compile: fix Compiler Directives typo
cmd/compile: fix Compiler Directives typo

Change-Id: I098b3c627c2142affd4e800a2c1f37e00f3775c5
Reviewed-on: https://go-review.googlesource.com/c/140777
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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