Mark more sdk targets as PHONY

These are used in various dist-for-goal targets even if we're not
currently building the sdks, so they always need to be marked with
.PHONY.

Test: m dist
Change-Id: I1e11ae37c6d0fd6ef8a3e293cf7409773c1bf3ab
diff --git a/core/main.mk b/core/main.mk
index fd62a98..1b00124 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -1391,7 +1391,7 @@
 .PHONY: docs
 docs: $(ALL_DOCS)
 
-.PHONY: sdk
+.PHONY: sdk win_sdk winsdk-tools
 ALL_SDK_TARGETS := $(INTERNAL_SDK_TARGET)
 sdk: $(ALL_SDK_TARGETS)
 $(call dist-for-goals,sdk win_sdk, \