Update NDK library list

Apparently this isn't autogenerated based on the list of ndk_library
modules?

Fixes: 124019854
Test: try to use libsync from a cc_library with sdk_version: "current"
Change-Id: I5016e1b7d77ed9255bf4b185c168efe8d0b73d12
diff --git a/cc/ndk_library.go b/cc/ndk_library.go
index 1b09f88..3ae4452 100644
--- a/cc/ndk_library.go
+++ b/cc/ndk_library.go
@@ -53,6 +53,7 @@
 		"OpenMAXAL",
 		"OpenSLES",
 		"stdc++",
+		"sync",
 		"vulkan",
 		"z",
 	}