Build under regular user again

Previously this didn't work because Docker still creates missing target folders as root instead of as mapped user.

Manually creating the folder seems to fix that.

build.sh

@@ -23,7 +23,9 @@ else
 fi
 
 docker build -t web-gphoto2 - <Dockerfile
+mkdir -p deps/.emcache
 docker run --rm $DOCKER_INTERACTIVE_OPTS \
+	-u $(id -u):$(id -g) \
 	-v $PWD:/src \
 	-v $PWD/deps/.emcache:/emsdk/upstream/emscripten/cache \
 	web-gphoto2 \