themes: convert theme copying to a golang module

Change-Id: I0a1e4b79109cf9db93acb0575200f4ec8f72d3a2
diff --git a/gui/Android.bp b/gui/Android.bp
index e5b97d8..c66cae4 100644
--- a/gui/Android.bp
+++ b/gui/Android.bp
@@ -7,7 +7,9 @@
         "soong-cc"
     ],
     srcs: [
-        "libguitwrp_defaults.go"
+        "libguitwrp_defaults.go",
+        "../soong/copy.go",
+        "../soong/makevars.go"
     ],
     pluginFor: ["soong_build"]
 }
@@ -22,7 +24,8 @@
     cflags: [
         "-fno-strict-aliasing", 
         "-Wno-implicit-fallthrough",
-        "-D_USE_SYSTEM_ZIPARCHIVE"
+        "-D_USE_SYSTEM_ZIPARCHIVE",
+        "-DTWRES=\"/twres/\""
     ],
     include_dirs: [
         "bootable/recovery/crypto/scrypt/lib/util",