Do not error when cleanup fails; fixes #17

Author: jeroen

src/Makevars

@@ -11,8 +11,8 @@ export CARGO_HOME=$(PWD)/.cargo
 
 $(STATLIB):
 	PATH="$(HOME)/.cargo/bin:$(PATH)" cargo build --release --manifest-path=myrustlib/Cargo.toml
-	rm -Rf $(CARGO_HOME)
-	rm -Rf $(LIBDIR)/build
+	rm -Rf $(CARGO_HOME) || true
+	rm -Rf $(LIBDIR)/build || true
 
 clean:
 	rm -Rf $(SHLIB) $(STATLIB) $(OBJECTS) myrustlib/target