rust: Add rustlibs auto dependency selection

Adds the rustlibs dependency type which will automatically select
between rlib and dylib based on the type of the library.

Bug: 143217452
Test: cd external/rust; mma
Change-Id: I97faadae98bf957090a32939cfb2d3a10f74a057
diff --git a/rust/binary.go b/rust/binary.go
index 56d6f0b..a1cd410 100644
--- a/rust/binary.go
+++ b/rust/binary.go
@@ -131,3 +131,11 @@
 func (binary *binaryDecorator) coverageOutputZipPath() android.OptionalPath {
 	return binary.coverageOutputZipFile
 }
+
+func (binary *binaryDecorator) autoDep() autoDep {
+	if binary.preferDynamic() {
+		return dylibAutoDep
+	} else {
+		return rlibAutoDep
+	}
+}