[centos] move cuda installation before toolchain installation

So changing toolchain can reuse cached cuda installation

centos/Dockerfile

@@ -4,13 +4,23 @@ FROM centos:7
 LABEL maintainer="Moritz Maxeiner <moritz.maxeiner@fu-berlin.de>"
 LABEL authors="Moritz Maxeiner <moritz.maxeiner@fu-berlin.de>"
 
-# GCC
 ENV BASH_ENV "/etc/profile"
 RUN yum install -y \
         centos-release-scl \
         epel-release && \
     yum update -y && \
-    yum install -y \
+    yum clean all
+
+# CUDA
+RUN yum install -y dkms && \
+    rpm -ivh https://developer.download.nvidia.com/compute/cuda/repos/rhel7/x86_64/cuda-repo-rhel7-10.1.243-1.x86_64.rpm && \
+    yum install -y cuda-10-1 && \
+    rpm -ivh http://developer.download.nvidia.com/compute/machine-learning/repos/rhel7/x86_64/nvidia-machine-learning-repo-rhel7-1.0.0-1.x86_64.rpm && \
+    yum install -y libcudnn7-devel-7.6.5.32-1.cuda10.1 && \
+    yum clean all
+
+# GCC
+RUN yum install -y \
         kernel && \
     yum install -y \
         devtoolset-8 \
@@ -57,15 +67,6 @@ RUN yum install -y \
         && \
     yum clean all
 
-# CUDA
-RUN yum install -y dkms && \
-    cd /tmp && \
-    rpm -ivh https://developer.download.nvidia.com/compute/cuda/repos/rhel7/x86_64/cuda-repo-rhel7-10.1.243-1.x86_64.rpm && \
-    yum install -y cuda-10-1 && \
-    rpm -ivh http://developer.download.nvidia.com/compute/machine-learning/repos/rhel7/x86_64/nvidia-machine-learning-repo-rhel7-1.0.0-1.x86_64.rpm && \
-    yum install -y libcudnn7-devel-7.6.5.32-1.cuda10.1 && \
-    yum clean all
-
 # FFmpeg
 RUN version=4.2.1 && \
     yum install -y \