Add 'gitonly_deps' list to rebar config/script (#3391)

Add list of dependencies that should only be built from git, to support
building with rebar3 where deps do not have hex packages (or where the
package versions do not directly map to git tags).

This is required for elixir and luerl deps.

rebar.config

@@ -61,6 +61,8 @@
         {yconf, ".*", {git, "https://github.com/processone/yconf", {tag, "1.0.7"}}}
        ]}.
 
+{gitonly_deps, [elixir, luerl]}.
+
 {if_var_true, latest_deps,
  {floating_deps, [cache_tab,
                   eimp,

rebar.config.script

@@ -196,9 +196,14 @@ AppendList2 = fun(Append) ->
 	      end,
 
 Rebar3DepsFilter =
-fun(DepsList) ->
-	lists:map(fun({DepName, _, {git, _, {tag, Version}}}) ->
-			  {DepName, Version};
+fun(DepsList, GitOnlyDeps) ->
+	lists:map(fun({DepName, _, {git, _, {tag, Version}}} = Dep) ->
+			  case lists:member(DepName, GitOnlyDeps) of
+			      true ->
+				  Dep;
+			      _ ->
+				  {DepName, Version}
+                          end;
 		     (Dep) ->
 			  Dep
 		  end, DepsList)
@@ -367,8 +372,8 @@ Rules = [
 	  AppendList2(ProcssXrefExclusions), [], []},
 	 {[deps], [floating_deps], true,
 	  ProcessFloatingDeps, [], []},
-	 {[deps], IsRebar3,
-	  Rebar3DepsFilter, []},
+	 {[deps], [gitonly_deps], IsRebar3,
+	  Rebar3DepsFilter, [], []},
 	 {[deps], SystemDeps /= false,
 	  GlobalDepsFilter, []}
 	],