Add system/extras/simpleperf to Rust allowed paths

This is to allow simpleperf to export rust bindings for use by
profcollect.

Test: build
Change-Id: I187139d6133c144e86cbdb05d20c2515c189718e
diff --git a/rust/config/allowed_list.go b/rust/config/allowed_list.go
index 21df024..fc11d29 100644
--- a/rust/config/allowed_list.go
+++ b/rust/config/allowed_list.go
@@ -19,6 +19,7 @@
 		"prebuilts/rust",
 		"system/bt",
 		"system/extras/profcollectd",
+		"system/extras/simpleperf",
 		"system/hardware/interfaces/keystore2",
 		"system/security",
 		"system/tools/aidl",