message: clarify synthetic nature of dep
diff: @@ -29,6 +29,8 @@ flate2 = "1.0"
  fs2 = "0.4"
  git2 = "0.7.2"
  git2-curl = "0.8.1"
  +libgit2-sys = "0.7.5" # required only for minimal-versions. brought in by git2 and git2-curl.
  +libssh2-sys = "0.2.8" # required only for minimal-versions. brought in by libgit2-sys.
  glob = "0.2.11"
  hex = "0.3"
  home = "0.3"
  @@ -54,9 +56,6 @@ toml = "0.4.2"
  url = "1.1"
  clap = "2.31.2"
  unicode-width = "0.1.5"
  -libssh2-sys = "0.2.8"
  -libgit2-sys = "0.7.5"
  -gcc = "0.3.23"
  # Not actually needed right now but required to make sure that rls/cargo build
  # with the same set of features in rust-lang/rust
  @@ -67,7 +66,10 @@ core-foundation = { version = "0.6.0", features = ["mac_os_10_7_support"] }
  [target.'cfg(windows)'.dependencies]
  miow = "0.3.1"
  -cmake = "0.1.24" # git2 with min-dep on windows
  +
  +[target.'cfg(windows)'.dev-dependencies]
  +gcc = "0.3.23" # required only for minimal-versions on windows. brought in by flate2 and others.
  +cmake = "0.1.24" # required only for minimal-versions on windows. brought in as build-dependencie on libgit2-sys.
  [target.'cfg(windows)'.dependencies.winapi]
  version = "0.3"
  