Revert "Adds a workaround to fix version inconsistency"

This reverts commit bc98d2ffe8.

Reason for revert: It was much to my chagrin that I realized the main purpose of this build target is an actually an internal branch which has the changes which make S the default for Robolectric.  This will complicate things a little bit in the short term, but in principle, this revert can be merged over with those changes down the line.

Change-Id: I053a32d89bfdf33486d95a30b145eb3b6f57df1d

java/robolectric.go

@@ -389,10 +389,8 @@ func (r *robolectricRuntimes) GenerateAndroidBuildActions(ctx android.ModuleCont
 		}
 		runtimeFromSourceJar := android.OutputFileForModule(ctx, runtimeFromSourceModule, "")
 
-		// TODO(murj) Update this to ctx.Config().PlatformSdkCodename() once the platform
-		// classes like android.os.Build are updated to S.
 		runtimeName := fmt.Sprintf("android-all-%s-robolectric-r0.jar",
-			"R")
+			    ctx.Config().PlatformSdkCodename())
 		installedRuntime := ctx.InstallFile(androidAllDir, runtimeName, runtimeFromSourceJar)
 		r.runtimes = append(r.runtimes, installedRuntime)
 	}