Fix rugged dependency

[treydock]

Pre-Request Checklist

• Passes rubocop code analysis (try rubocop --auto-correct)
• Tests added or adapted (try rake test)
• Changes are reflected in the documentation
• User-visible changes appended to CHANGELOG.md

Description

The rugged gem now has 0.99.0 that requires a much newer cmake than is available on RHEL7:

[root@centos-7 /]# scl enable rh-ruby23 -- gem install --no-document oxidized
Building native extensions.  This could take a while...
ERROR:  Error installing oxidized:
	ERROR: Failed to build gem native extension.

    current directory: /opt/rh/rh-ruby23/root/usr/local/share/gems/gems/rugged-0.99.0/ext/rugged
/opt/rh/rh-ruby23/root/usr/bin/ruby -r ./siteconf20200312-1719-1x0mvem.rb extconf.rb
checking for gmake... yes
checking for cmake... yes
checking for pkg-config... yes
-- The C compiler identification is GNU 4.8.5
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
CMake Error at CMakeLists.txt:15 (CMAKE_MINIMUM_REQUIRED):
  CMake 3.5.1 or higher is required.  You are running version 2.8.12.2


-- Configuring incomplete, errors occurred!
See also "/opt/rh/rh-ruby23/root/usr/local/share/gems/gems/rugged-0.99.0/vendor/libgit2/build/CMakeFiles/CMakeOutput.log".
 -- /usr/bin/gmake
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib64
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/opt/rh/rh-ruby23/root/usr/bin/$(RUBY_BASE_NAME)
	--with-sha1dc
	--without-sha1dc
	--use-system-libraries
extconf.rb:23:in `sys': ERROR: '/usr/bin/gmake' failed (RuntimeError)
	from extconf.rb:107:in `block (2 levels) in <main>'
	from extconf.rb:103:in `chdir'
	from extconf.rb:103:in `block in <main>'
	from extconf.rb:100:in `chdir'
	from extconf.rb:100:in `<main>'

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /opt/rh/rh-ruby23/root/usr/local/lib64/gems/ruby/rugged-0.99.0/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /opt/rh/rh-ruby23/root/usr/local/share/gems/gems/rugged-0.99.0 for inspection.
Results logged to /opt/rh/rh-ruby23/root/usr/local/lib64/gems/ruby/rugged-0.99.0/gem_make.out

[wk]

There is no explicit backwards compatibility goal at this stage (seeing that RHEL8 is out), but since the intention was to match 0.28 and no features of newer versions are currently in use - this seems mostly harmless. Could you add a line to CHANGELOG.md mentioning this change (and reasoning) as part of this PR?

On a side note, since the required ruby comes from SCL already, is there a compelling reason not to also pull a newer CMake from SCL as well during install instead of locking down to an older version of rugged?

[treydock]

I updated CHANGELOG.

I only observed the newer cmake via SCL for RHEL7 via llvm-toolset-7-cmake package which is really odd way to go about getting newer cmake. Looks like cmake3 is available from EPEL, just not sure how to make a rubygem use a cmake3 binary instead of cmake. I use puppet for automation of oxidized (https://github.com/treydock/puppet-module-oxidized) and figured easier to fix rugged dependency than mess with other ways to get newer cmake.