cmd/compile: remove unused func nodfltconst
cmd/compile: remove unused func nodfltconst

Its only usage was removed in golang.org/cl/103860

Change-Id: I2a230b9475b0aadf3892b89f5e4ee6d4c5b70394
Reviewed-on: https://go-review.googlesource.com/c/go/+/172917
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
Run-TryBot: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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