Update cubeb-backend to workaround rust-lang/rust#58881 (BMO 1532645)

Author: ChunMinChang

Cargo.toml

@@ -9,7 +9,10 @@ crate-type = ["staticlib", "rlib"]
 [dependencies]
 atomic = "0.4"
 bitflags = "1.0"
-cubeb-backend = "0.5"
+# BMO 1532645: https://bugzilla.mozilla.org/show_bug.cgi?id=1532645
+# To workaround https://github.com/rust-lang/rust/issues/58881 and make `cubeb_logv!` work,
+# the minimal version of cubeb-backend is 0.5.1.
+cubeb-backend = "0.5.3"
 core-foundation-sys = { version = "0.6" }
 libc = "0.2"