fix: simulator and nix issues

Sources/WireGuardKitGo/Makefile

@@ -20,6 +20,7 @@ GOARCH_arm64 := arm64
 GOARCH_x86_64 := amd64
 GOOS_macosx := darwin
 GOOS_iphoneos := ios
+GOOS_iphonesimulator := ios
 
 build: $(DESTDIR)/libwg-go.a
 version-header: $(DESTDIR)/wireguard-go-version.h
@@ -29,6 +30,7 @@ export GOROOT := $(BUILDDIR)/goroot
 $(GOROOT)/.prepared:
 	[ -n "$(REAL_GOROOT)" ]
 	mkdir -p "$(GOROOT)"
+	chmod -R u+w "$(GOROOT)"
 	rsync -a --delete --exclude=pkg/obj/go-build "$(REAL_GOROOT)/" "$(GOROOT)/"
 	cat goruntime-*.diff | patch -p1 -f -N -r- -d "$(GOROOT)"
 	touch "$@"