themes: convert theme copying to a golang module

Change-Id: I0a1e4b79109cf9db93acb0575200f4ec8f72d3a2
diff --git a/soong/makevars.go b/soong/makevars.go
new file mode 100644
index 0000000..f453ed0
--- /dev/null
+++ b/soong/makevars.go
@@ -0,0 +1,14 @@
+package twrp
+
+import (
+	"android/soong/android"
+)
+
+func getMakeVars(ctx android.BaseContext, mVar string) string {
+	makeVars := ctx.Config().VendorConfig("makeVarsPlugin")
+	var makeVar = ""
+	if makeVars.IsSet(mVar) {
+		makeVar = makeVars.String(mVar)
+	}
+	return makeVar
+}