Use python:3.8.2-slim-buster Docker base image (#1095)

This doesn't come with any build dependencies by default, so this
clarifies what really is needed (and as you can see from the diff, not
much).

.circleci/config.yml

@@ -3,7 +3,7 @@ version: 2
 defaults: &defaults
   working_directory: ~/repo
   docker:
-    - image: iodide/pyodide-env:10
+    - image: iodide/pyodide-env:11
   environment:
     - EMSDK_NUM_CORES: 4
       EMCC_CORES: 4

Dockerfile

@@ -1,9 +1,10 @@
-FROM python:3.8.2-buster
+FROM python:3.8.2-slim-buster
 
 RUN apt-get update \
   && apt-get install -y --no-install-recommends \
                   # building packages
-                  bzip2 ccache clang-format-6.0 cmake f2c g++ gfortran libtinfo5 swig \
+                  bzip2 ccache clang-format-6.0 cmake f2c g++ gfortran git make \
+                  patch pkg-config swig unzip wget xz-utils \
                   # testing packages: libgconf-2-4 is necessary for running chromium
                   libgconf-2-4 chromium \
   && rm -rf /var/lib/apt/lists/*

run_docker

@@ -26,7 +26,7 @@ function error() {
 }
 
 
-PYODIDE_IMAGE_TAG="10"
+PYODIDE_IMAGE_TAG="11"
 PYODIDE_PREBUILT_IMAGE_TAG="0.16.1"
 DEFAULT_PYODIDE_DOCKER_IMAGE="iodide/pyodide-env:${PYODIDE_IMAGE_TAG}"
 DEFAULT_PYODIDE_SYSTEM_PORT="8000"