update git installation on centos 7 to git 2.x

motivation: centos 7 ships with git 1.x which is too old for the toolchain usage

chages:
* use RHL software collections to install git 2.x
* add symlink since collections install in /opt (TBD better solution)

Author: tomerd

nightly-main/centos/7/Dockerfile

@@ -2,10 +2,12 @@ FROM centos:7
 LABEL maintainer="Swift Infrastructure <[email protected]>"
 LABEL description="Docker Container for the Swift programming language"
 
+RUN yum install -y centos-release-scl-rh
+
 RUN yum install shadow-utils.x86_64 -y \
   binutils \
   gcc \
-  git \
+  rh-git227-git \
   glibc-static \
   libbsd-devel \
   libcurl-devel \
@@ -20,6 +22,8 @@ RUN yum install shadow-utils.x86_64 -y \
   sqlite \
   zlib-devel
 
+RUN ln -s /opt/rh/rh-git227/root/bin/git /usr/bin/git
+
 RUN sed -i -e 's/\*__block/\*__libc_block/g' /usr/include/unistd.h
 
 # Everything up to here should cache nicely between Swift versions, assuming dev dependencies change little