Add gcc to docker

Author: ildus

Dockerfile.tmpl

@@ -1,12 +1,7 @@
 FROM postgres:${PG_VERSION}-alpine
 
-ENV PYTHON=python${PYTHON_VERSION}
-RUN if [ "${PYTHON_VERSION}" = "2" ] ; then \
-	apk add --no-cache gcc curl python2 py-virtualenv py-pip; \
-	fi
-RUN if [ "${PYTHON_VERSION}" = "3" ] ; then \
-	apk add --no-cache gcc curl python3 py-virtualenv; \
-	fi
+ENV PYTHON=python3
+RUN apk add --no-cache build-base curl python3 py-virtualenv python3-dev musl
 ENV LANG=C.UTF-8
 
 RUN mkdir -p /pg