Merge pull request #191 from compnerd/centos-diff

CentOS: add diffutils

Author: shahmishal

swift-ci/master/centos/8/Dockerfile

@@ -11,6 +11,7 @@ RUN yum install --enablerepo=PowerTools -y \
     autoconf              \
     clang                 \
     cmake                 \
+    diffutils             \
     git                   \
     libbsd-devel          \
     libcurl-devel         \
@@ -40,4 +41,4 @@ RUN ln -s /usr/bin/python2 /usr/bin/python
 
 USER build-user
 
-WORKDIR /home/build-user
+WORKDIR /home/build-user