Add the Phobos v3 unit tests to the regular unittest build.

I'm sure that we'll need to rework the build stuff at some point here
(both for Phobos v2 and v3), but this gets the v3 tests run by the v2
Makefile so that the CI will build and run them.

Makefile

@@ -337,6 +337,7 @@ else
 unittest : unittest-debug unittest-release
 unittest-%:
 	$(MAKE) unittest OS=$(OS) MODEL=$(MODEL) DMD=$(DMD) BUILD=$*
+	dmd -run build_v3.d unittest-$*
 endif
 
 ################################################################################

build_v3.d

@@ -22,8 +22,16 @@ int main(string[] args)
     bool buildRelease = false;
     if (args.length > 1)
     {
-        buildUnittest = args[1] == "unittest";
-        buildRelease = args[1] == "release";
+        switch(args[1])
+        {
+            // FIXME unittest should build both debug and release, but that
+            // requires more extensive changes.
+            case "unittest": buildUnittest = true; break;
+            case "unittest-debug": buildUnittest = true; break;
+            case "unittest-release": buildUnittest = true; goto case "release";
+            case "release": buildRelease = true; break;
+            default: break;
+        }
     }
 
     string argFilePath = buildNormalizedPath(getcwd(), "phobosbuildargs.txt");
@@ -69,7 +77,6 @@ int main(string[] args)
     {
         argFile.writeln("-main");
         argFile.writeln("-unittest");
-        argFile.writeln("-debug");
 
         version(Windows)
         {
@@ -80,17 +87,19 @@ int main(string[] args)
             argFile.writeln("-of=unittest");
         }
     }
-    else if (buildRelease)
+    else
     {
-        argFile.writeln("-release -O");
         argFile.writeln("-lib");
-        argFile.writeln("-of=libphobos3");
+        argFile.writefln("-of=libphobos3%s", buildRelease ? "" : "-debug");
+    }
+
+    if (buildRelease)
+    {
+        argFile.writeln("-release -O");
     }
     else
     {
         argFile.writeln("-debug");
-        argFile.writeln("-lib");
-        argFile.writeln("-of=libphobos3-debug");
     }
 
     argFile.flush();