rust: Set the rpath for rust_test modules

Set the rpath for rust_test modules to allow the runtime linker to find
libraries defined in data_libs.

Bug: 171710847
Test: m
Change-Id: I1b67f0256826a3161a4c3193076e2ee4aef8c093
diff --git a/rust/test.go b/rust/test.go
index 9833ffd..25ea463 100644
--- a/rust/test.go
+++ b/rust/test.go
@@ -242,6 +242,10 @@
 		flags.RustFlags = append(flags.RustFlags, "-Z panic_abort_tests")
 	}
 
+	// Add a default rpath to allow tests to dlopen libraries specified in data_libs.
+	flags.GlobalLinkFlags = append(flags.GlobalLinkFlags, `-Wl,-rpath,\$$ORIGIN/lib64`)
+	flags.GlobalLinkFlags = append(flags.GlobalLinkFlags, `-Wl,-rpath,\$$ORIGIN/lib`)
+
 	return flags
 }