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are always evaluated because there is no rule to create a `.PHONY` file and that will force make to think the rule is out of date and needs to be rebuilt.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 our virtual targets with `.PHONY` by declaring the `.PHONY` dependency immediately above the make rule. Before, some `.PHONY` associations were inline (as this patch establishes). Others were defined in common blocks. Even others were defined incorrectly, actually assigning a `.PHONY` variable instead of operating on the make target! Before, not all virtual targets had `.PHONY` associations. And there were some defined `.PHONY` associations in common blocks whose targets had long been deleted. Hopefully the unified convention will prevent things from getting out of sync going forward. Why do this? First, consistency is good. Now people don't have to know to look for a separate block of `.PHONY` attribution. Hopefully this prevents missing `.PHONY` annotations going forward. Second, there are some cases where virtual make targets are virtual / phony when they shouldn't be. These are creating race conditions and avoidable rebuilds across multiple `make` invocations. e.g. a `make all` + `make install` invocation will perform PGO+BOLT if BOLT is enabled because `profile-opt` and `bolt-opt` are phony and always invoked. I plan follow-ups to this cleanup to fix some bugs I've run into.