Use $(TOOLSBINDIR)/protoc. MacOS fails to use PATH setting.
Use $(TOOLSBINDIR)/protoc. MacOS fails to use PATH setting.

The PATH setting in `tools.mk` doesn't have any effect when using Make
3.8.1 (the default on MacOS Catalina). This change ensures that the
correct `protoc` is used.

datawire/telepresence,datawire/telepresence,datawire/telepresence