Implement bp2build for prebuilt_etc_xml

Bug: 237039154
Test: xml_conversion_test.go & bp2build
Change-Id: I1f2c57b9532138f73041d8fc08feea3f66b2ebbc
diff --git a/android/allowlists/allowlists.go b/android/allowlists/allowlists.go
index 6a8db79..40e366e 100644
--- a/android/allowlists/allowlists.go
+++ b/android/allowlists/allowlists.go
@@ -462,6 +462,10 @@
 		"libavb",
 		"avb_headers",
 
+		//external/libxml2
+		"xmllint",
+		"libxml2",
+
 		//external/fec
 		"libfec_rs",