gh-104490: Consistently define phony make targets (#104491)

By convention make targets that don't refer to a file have a dependency
on the fake .PHONY target/file. This ensures that these targets are
always evaluated because there is no rule to create a .PHONY file
and that will force make to think the rule is out of date and needs
to be rebuilt.

This commit consistently associates virtual targets with .PHONY by
declaring the .PHONY dependency immediately above the make rule. This
should avoid race conditions and avoidable rebuilds across multiple make
invocations.