Add stdlibs property for Rust build rules.

This lets no_std crates depend on system crates like core and alloc.

Bug: 223152204
Test: built pVM firmware skeleton with rust_ffi_static rule
Change-Id: I0f9b0ab3f5e3289fb8ce66f28d779bcf62a7181f
diff --git a/rust/rust.go b/rust/rust.go
index f40f1a8..1c718a4 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -968,6 +968,7 @@
 	deps.ProcMacros = android.LastUniqueStrings(deps.ProcMacros)
 	deps.SharedLibs = android.LastUniqueStrings(deps.SharedLibs)
 	deps.StaticLibs = android.LastUniqueStrings(deps.StaticLibs)
+	deps.Stdlibs = android.LastUniqueStrings(deps.Stdlibs)
 	deps.WholeStaticLibs = android.LastUniqueStrings(deps.WholeStaticLibs)
 	return deps