bp2build: allowlist system/memory/libmemunreachable

A new dep on this package was added in https://android-review.googlesource.com/c/platform/bionic/+/2092709

Started failing from ab/8573658

Change-Id: If53bc4d75f95aeca9f0dcf007d7ed700860058eb
Test: CI
diff --git a/android/allowlists/allowlists.go b/android/allowlists/allowlists.go
index 5384b09..9aae6fd 100644
--- a/android/allowlists/allowlists.go
+++ b/android/allowlists/allowlists.go
@@ -179,6 +179,7 @@
 		"system/libprocinfo":                                 Bp2BuildDefaultTrue,
 		"system/libziparchive":                               Bp2BuildDefaultTrueRecursively,
 		"system/logging/liblog":                              Bp2BuildDefaultTrueRecursively,
+		"system/memory/libmemunreachable":                    Bp2BuildDefaultTrueRecursively,
 		"system/sepolicy/apex":                               Bp2BuildDefaultTrueRecursively,
 		"system/timezone/apex":                               Bp2BuildDefaultTrueRecursively,
 		"system/timezone/output_data":                        Bp2BuildDefaultTrueRecursively,