[PATCH] docker: pyenv: build at make -j$(nproc)

[Daniel Axtens]

This speeds up builds. I haven't measured by how much, but I have
observed 8 threads being complied rather than 1 on my laptop.

Signed-off-by: Daniel Axtens <dja at axtens.net>
---
 tools/docker/Dockerfile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/docker/Dockerfile b/tools/docker/Dockerfile
index 35324b13c66a..dfc9c2f3dab1 100644
--- a/tools/docker/Dockerfile
+++ b/tools/docker/Dockerfile
@@ -43,7 +43,8 @@ RUN curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-instal
     git clone https://github.com/momo-lab/xxenv-latest $PYENV_ROOT/plugins/xxenv-latest && \
     pyenv update
 
-RUN pyenv latest install 2.7 && \
+RUN export MAKE_OPTS=-j$(nproc) && \
+    pyenv latest install 2.7 && \
     pyenv latest install 3.5 && \
     pyenv latest install 3.6 && \
     pyenv latest install 3.7
-- 
2.20.1