/tmp should be bind mounted to allow more space

Makefile

@@ -14,6 +14,9 @@ build:
 	mkswap swap
 	swapon swap
 
+	mkdir tmp
+	mount --bind tmp /tmp
+
 	mkdir -p ../go/go/src/github.com/prometheus
 	mkdir -p ../go/gocache
 	tar xf prometheus-2.19.2.tar.gz -C ../go/go/src/github.com/prometheus
@@ -25,5 +28,8 @@ build:
 	rm -f /usr/local/share/.yarnrc
 	rm -rf ../go/gocache
 
+	umount /tmp
+	rm -rf tmp
+
 	swapoff swap
 	rm -rf swap